Thrombosis and Bleeding Disorders: Theory and Methods

By Erwin Deutsch

Thrombosis and Bleeding Disorders compiles the laboratory and research aspects of thrombosis and hemorrhagic disorders in humans. This book presents reviews of the underlying theory, physiology, and biochemistry of hemostasis and thrombosis, including the enzymology of blood coagulation and fibrinolysis. This compilation is divided into three levels of specific purposes. First is to provide the most reliable and widely accepted laboratory assays of undisputed diagnostic clinical value, which provides newcomers in the field and experienced workers in the coagulation laboratory with a reference manual to everyday work in a clinically-oriented environment. Second is to review and sketch in outline the theoretical sections focusing on mechanisms. Finally, this text aims to include a systematic review of the most successful purification techniques for individual coagulation factors and moieties of the fibrinolytic enzyme system. This publication is beneficial to medical students and clinicians concerned with human blood coagulation.

• Language: English
• Publisher: Academic Press
• Release date: Jun 28, 2014
• ISBN: 9781483261287

Book preview

Thrombosis and Bleeding Disorders

Theory and Methods

Nils U. Bang

Fritz K. Beller

Erwin Deutsch

Eberhard F. Mammen

Academic Press

Table of Contents

Cover image

Title page

Copyright

Preface

Contributors

Chapter 1: Physiology and Biochemistry of Blood Coagulation

Publisher Summary

I Introduction

II Historical Aspects of Blood Coagulation

III Nomenclature

IV Physicochemical Properties of Coagulation Constituents

V Activation of Prothrombin

VI Conclusions and Summary

Chapter 2: Equipment and General Requirements for the Coagulation Laboratory

Publisher Summary

I Introduction

II Equipment

III Collection of Blood

IV Cleaning and Preparation of Glassware

V Buffer Solutions

VI Anticoagulants

VII Ion Exchange Resins

Chapter 3: Clotting Time Techniques

Heparin Sensitized Clotting Time

Thrombelastography

Partial Thromboplastin Time Techniques

Prothrombin Consumption Tests

Thrombin and Thromboplastin Generation Techniques

One-Stage Prothrombin Time Techniques

Chapter 4: Purification of Prothrombin

Purification of Prethrombin Modified Zymogen

Purification of Thrombin

Purification of Ac-Globulin (Factor V)

Purification of Factor VIII

Purification of Factor VII and Factor IX

Purification of Factor X (Autoprothrombin III-C)

Purification of Hageman Factor (factor XII)

Purification of Plasma Thromboplastin Antecedent (PTA, factor XI)

Purification of Tissue Thromboplastin

Purification of Platelet Factor 3

Chapter 5: Assay for Prothrombin

Thrombin Clotting Assays

Assays of Factor V

Assays for Antihemophilic Factor (Factor VIII)*

Addendum

Assays for Factors VII and X

Assays for Factor IX: (Christmas Factor, Plasma Thromboplastin Component [PTC], Platelet Cofactor II, Antihemophilic Globulin B [AHF B])

Assays for Autoprothrombin I, II, III, C, and Prethrombin

Assays for Hageman Factor (factor XII) and Plasma Thromboplastin Antecedent (factor XI)*

Chapter 6: Fibrinogen

Fibrinogen and Fibrin Derivatives

Isolation and Purification of Fibrin Stabilizing Enzyme (F XIII, FSF, Laki-Lorand Factor, Fibrinase)

Assays for Fibrin Stabilizing Factor (Factor XIII)

Chapter 7: Determination of Antithrombin

Heparin Assays in Blood

Circulating Anticoagulants

Chapter 8: Physiology and Biochemistry of Fibrinolysis

Fibrinolytic Activity in Whole Blood, Dilute Blood, and Euglobulin Clot Lysis Time Tests

The Fibrin Plate Method for Assay of Fibrinolytic Agents*

The Purification of Profibrinolysin and Fibrinolysin

Caseinolytic Techniques*

Plasminogen Assays Using Fibrin as a Substrate

The Esterase Assay of Enzymes of Blood Clotting and Lysis

Assay of the Plasminogen Activator in Tissues*

Assay Methods for Individual Fibrinolytic Components - Urokinase and Streptokinase

Assay for Plasminogen Activators with Labelled Fibrin Substrates

Streptokinase Tolerance Test

Determination of Inhibitors of Fibrinolysis

Differentiation Between Intravascular Coagulation and Intravascular Proteolysis

Chapter 9: Hemostasis

Bleeding Time Techniques

Tests for Capillary Fragility and Resistance

Platelet Count Techniques, Platelet Adhesiveness and Aggregation Tests

Assays for Platelet Factors

Clot Retraction

Electron Microscopic Techniques for Blood Platelets Fibrinogen and Fibrin

Chapter 10: Immunologic Techniques

Immune Assay of Tissue Thromboplastin

Chapter 11: Thrombosis

Methods for the Experimental Study of Intravascular Thrombus Formation

Experimental Animal Models for the Production of Disseminated Intravascular Coagulation

Demonstration of Plasma Proteins in Microscopic Sections with Emphasis on the Identification of Fibrin

Index

Copyright

Academic Press, Inc.

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Georg Thieme Verlag

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Product names which are in fact registered trademarks have not been specifically designated as such. Thus, in those cases where a product has been referred to by its registered trademark it cannot be concluded that the name used is public domain. The same applies as regards patents or registered designs.

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© Academic Press, New York 1971, Printed in Germany by C. F. Rees GmbH, 7920 Heidenheim (Brenz), Germany

Library of Congress Catalog Card Number: 75 141604

Academic Press Inc.: ISBN 0 12 077750 9

Georg Thieme Verlag: ISBN 3 13 459201 0

Preface

This volume represents an international effort to bring together the most recent information on the laboratory and research aspects of thrombosis and hemorrhagic disorders in man. We have attempted in this text to provide not only a detailed description of the most widely-used laboratory assays but also to bring this technical information into its proper perspective by presenting reviews of the underlying theory, the physiology and biochemistry of hemostasis and thrombosis, the enzymology of blood coagulation and fibrinolysis.

The last 50 years have taught us the complexity of the physical-chemical phenomena resulting in the conversion of the soluble plasma protein fibrinogen into the insoluble network gel fibrin; more recently, we have also taken great strides to improve our knowledge of the biochemistry of the platelet aggregation phenomenon, a necessary prerequisite for normal hemostasis as well as thrombosis. The complexity of the systems under investigation has resulted in the development of a multitude of assays which often have lacked the specificity and reproducibility required for a sound and exacting enzyme kinetic analysis of the systems under investigation. The lack of such specific and quantitative techniques, the lack of the precise tools which must be at hand for the accurate analysis of any biological phenomenon has lead, in turn, to the development of a confusing number of conflicting or only partly compatible theories of the basic mechanisms involved in blood coagulation. And yet, the wide variety of semiquantitative test systems developed over the years have been of indisputable value and have helped to advance our knowledge in important clinical areas. The battery of laboratory tests currently available has made it possible to establish with great accuracy the differential diagnoses between the hemophilias and hemophilia-like syndromes. On the other hand, it can be argued whether these widely-used laboratory assays and the clinical knowledge which has emerged as a consequence of their wide-spread use has contributed in any lasting way to the fundamental theories of underlying mechanisms. We must also at this point ask ourselves whether the laboratory methodology which has contributed so significantly to the understanding of clinical problems of hemorrhagic states, whether all this progress has brought us any closer to a truer understanding of thrombosis in vivo.

It appears to most serious workers in the field today that the final classification of the coagulation mechanism can be achieved only when all the procoagulants alleged to be parts of the system on the basis of clinical observations of the hemophilias, when all of these procoagulants can be made available as purified homogeneous proteins possessing the theoretically maximum specific activities. Only the future will tell whether the understanding of the exact enzymic mechanisms making these systems operative will in turn provide the key to the many unresolved questions of thrombogenesis in man.

It is on this background that we chose to organize this textbook at three levels for three specific purposes. First, it has been our intention to compile the most reliable, most widely-accepted laboratory assays of undisputed diagnostic clinical value to provide the newcomer in the field as well as the more experienced worker in the coagulation laboratory with a reference manual as a guide to his everyday work in a clinically-oriented environment.

Secondly, we hope with the theoretical sections focusing on mechanisms to give our readership inside and outside the field an up-to-date review of the current state of the art, to sketch in outline the appearance of these systems as they present themselves today on the basis of the best currently available biochemical tools and assay systems. We are clearly aware of the deficiencies in these presentations and the magnitude of future achievements necessary to fill the gaps in our basic comprehension of blood coagulation.

Thirdly, we decided to include a systematic review of the most modern and successful purification techniques for individual coagulation factors and moieties of the fibrinolytic enzyme system, hoping thereby to provide the serious student of human blood coagulation with a reference list of the tools which he must develop to further advance our knowledge in the field.

This book will see the light of day only because of the unstinted efforts of and serious dedication to the job at hand from all of our contributors. We wish to take this opportunity to extend to all contributors our grateful appreciation for their generosity with their time and efforts, their patience and courtesy in spite of the delays and problems which we encountered in the course of preparing this volume.

July, 1970

The Editors

Contributors

CLARA M. AMBRUS, M.D., Ph.D.,     Associate Research Prof. of Pediatrics, State University of New York at Buffalo, Principle Cancer Research Scientist, Roswell Park Memorial Institute, 666 Elm Street, Buffalo, New Qork 14203, USA

TAGE ASTRUP, Ph.D.,     Director of Research, The James F. Mitchell Foundation, Institute for Medical Research, 5401 Western Avenue N. W., Washington D. C. 20015, USA

NILS U. BANG, M.D.,     Associate Professor of Medicine, Lilly Laboratory for Clinical Research, Marion County General Hospital and, Indiana University Medical Center, Indianapolis, Indiana 46202 USA

MARION I. BARNHART, Ph.D.,     Professor of Physiology and Pharmacology Wayne State University School of Medicine, 1400 Chrysler Freeway, Detroit, Michigan 48207, USA

FRITZ K. BELLER, M.D., Med. Sci. D.,     Professor of Obstetrics and Cynecology, New York University School of Medicine, Career Scientist of the Health, Research Council of the City of New York (I 296), New York, New York 10016, USA

GUENTHER BENEKE, M.D.,     Professor of Pathology, Leiter der Abteilung für Pathologie II der, Universität Ulm Head, Department of Pathology II, University of Ulm, 79 Ulm/Donau Steinhoevelstr. 9, Germany

M. BETTEX-GALLAND, Ph.D.,     Research Associate, Anatomisches Institut der Universität, Department of Normal Anatomy, University of Berne, Buehstr. 26 3000 Bern, Switzerland

K. CHRISTIAN BORCHGREVINK, M.D.,     Professor, Institute of General Practice, Fr. Stangs gt 11/13, Oslo 2, Norway

PIETER BRAKMAN, M.D., Ph.D.,     Senior Investigator, The James F. Mitchell Foundation, Institute for Medical Research, 5401 Western Avenue N. W., Washington, D. C. 20015, USA

ERWIN DEUTSCH, M.D.,     Professor, Head of the First Department of Medicine, University of Vienna, Lazarettgasse 14 A 1090 Vienna, Austria

A.S. DOUGLAS, BSC, M.D. FRCP, F. C. Path.,     Professor of Medicine, University of Glasgow, Royal Infirmary, 86 Castle Street, Glasgow C 4, Scotland

F. DUCKERT, PD, Ph.D.,     Head of the Coagulation and Fibrinolysis, Laboratories Department of Internal Medicine, University of Basel, Bürgerspital, Medizinische Universitäts-Klinik, 4000 Basel, Switzerland

WALTER FISCHBACHER, M.D.,     Chief of Service, Bürgerspital St. Gallen, 9000 St. Gallen, Switzerland

CHARLES D. FORBES, M.B., CLB, MRCP,     Registrar in Medicine, Glasgow Royal Infirmary, 86 Castle Street, Glasgow C 4, Scotland

PIA GLAS, M.D.,     James F. Mitchell Foundation, Institute for Medical Research, 5401 Western Avenue N. W., Washington, D. C. 20015, USA

JOHS GORMSEN, M.D.,     Co-chairman, Medical Department, Sundby Hospital, 2300 Copenhagen S, Denmark

HENNER GRAEFF, M.D., P.D.,     I. Department of Obstetrics and Gynecology, Maistr. 11, 8 München, Germany

JARY L. GRAMMENS, Ph.D.,     Department of Physiology and Pharmacology, Wayne State University School of Medicine, 1400 Chrysler Freeway, Detroit, Michigan 48207, USA

M.D. HALBERSTADT, PD,     Assistant, Department of Obstetrics and Gynecology, Ludwig-Rehn-Str., Frankfurt/Main, Germany

HELMUT HARTERT, M.D.,     Chief of Service, City Hospital Kaiserslautern, Clinical Professor of Medicine, Saar University, Turmstr. 45, Kaiserslautern, Germany

P.J. HEBERLEIN, Ph.D.,     Deceased 1969, Research Associate, Department of Physiology and Pharmacology, Wayne State University School of Medicine, 1400 Chrysler Freeway, Detroit, Michigan 48207, USA

L. RAYMOND HENRY, Ph.D.,     Associate Professor, Department of Physiology and Pharmacology, Wayne State University School of Medicine, 1400 Chrysler Freeway, Detroit, Michigan 48207, USA

HERBERT I. HOROWITZ, M.D.,     Hematologist, Bronx-Lebanon Hospital Center, Clinical Assistant Professor of Medicine, Cornell Medical College, 1276 Fulton Avenue, Bronx, New York 10456, USA

ROLF M. HUSBY, Ph.D.,     Senior Biochemist, Lilly Laboratory for Clinical Research, Eli Lilly and Co., Indianapolis Ind. 46206, USA

ERIK J. JORPES, M.D.,     Emeritus Professor of Biochemistry, Karolinska Institutet, Stockholm 60, Torsgatan 8 11123 Stockholm, Sweden

DANIEL L. KLINE, Ph.D.,     Professor and Chairman, Department of Physiology, University of Cincinnati, College of Medicine, Eden & Bethesda Avenues, Cincinnati, Ohio 45219, USA

PREBEN KOK, M. Sc.,     Investigator, James F. Mitchell Foundation, Institute for Medical Research, 5401 Western Avenu N. W., Washington, D. C. 20015, USA

ROBERT D. LANGDELL, M.D.,     Professor of Pathology, School of Medicine, University of North Carolina, Chapel Hill, N. C. 27514, USA

KLAUS LECHNER, M.D.,     Assistant, First Department of Medicine, University of Vienna, 1090 Vienna, Austria, Lazarettgasse 14

MASAHIRO MAKI, M.D., Ph.D.,     Associate Professor, Department of Obstetrics and Gynecology, Hirosaki University School of Medicine, 2 Sagara-cho, Hirosaki, Japan

Z.S. LATALLO, M.D., Ulica Dorodna 16, Warszawa 9, Poland

EBERHARD F. MAMMEN, M.D.,     Professor of Pathology, Physiology and Pharmacology, Wayne State University School of Medicine, 1400 Chrysler Freeway, Detroit, Michigan 48207, USA

LOWELL E. McCOY, Ph.D.,     Assistant Professor, Department of Physiology and Pharmacology, Wayne State University School of Medicine, 1400 Chrysler Freeway, Detroit, Michigan 48207, USA

CAMPBELL W. McMILLAN, M.D.,     Associate Professor of Pediatrics, Associate Director Clinical Research Unit, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27514, USA

MILTON M. MOZEN, Ph.D.,     Director Biochemical Research Cutter Laboratories, Fourth and Parker Streets, Berkeley, California 94710, USA

GENESIO MURANO, Ph.D.,     Research Associate, Department of Physiology and Pharmacology, Wayne State University School of Medicine, 1400 Chrysler Freeway, Detroit, Michigan 48207, USA

J.R. O’BRIEN, MA, DM. MRCS, LRCP F.C. Path.,     Consultant Hematologist, Portsmouth and Isle of Wight Area Pathology Service, Central Laboratory St. Mary’s General Hospital, (East Wing), Milton Road, Portsmouth, England

GEORGE D. PENICK, M.D.,     Professor of Pathology, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27514, USA

OSCAR D. RATNOFF, M.D.,     Professor of Medicine, Career Investigator of the American Heart, Association Case Western Reserve University School of Medicine, University Hospitals of Cleveland, Cleveland, Ohio 44106, USA

CHARLES RIZZA, R.C., M.D. MRCP,     Consultant Physician, Oxford Hemophilia Centre, Clinical Lecturer in Hematology at the University of Oxford, Oxford Haemophilia Centre, Churchill Hospital, Headington, Oxford, England

HAROLD R. ROBERTS, M.D.,     Associate Professor of Medicine and Pathology, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27514, USA

HEINZ SCHRÖER, M.D.,     Scientific Advisor and Professor, Physiologisches Institut, Universität Würzburg, Department of Physiology, University of Würzburg, Roentgenring 9 8700 Würzburg, Germany

GERHARD H. SCHWICK, Ph.D.,     Director of Research, Behring Werke Dozent, University of Marburg, 355 Marburg/Lahn, Georg-Voigt-Str. 69, Germany

J.J. SIXMA, M.D., Ph.D.,     Head of the Division of Haemostasis, Consulting Physician in Internal Medicine, Interne Klinik Akademisches Krankenhaus Utrecht, Holland

RAPHAEL N. SHULMAN, M.D.,     Chief Clinical Hematology Branch, National Institute of Arthritis and Metabolic, Diseases National Institutes of Health, Clinical Center, NIH 10-9N250, Bethesda, Maryland 20014, USA

RALPH SPIELVOGEL ARTHUR, M.D.,     Associate Hematologist, The Bronx-Lebanon Hospital, Instructor in Medicine, New York College of Medicine, 1650 Grand Concourse, Bronx, New York, USA

WILLIAM E. STEHBENS, M.D., Ph.D.,     Professor of Pathology, Director of Electron Microscopy Unit, Veterans Administration Hospital Albany, New York 12208, USA

DEMETRIOS C. TRIANTAPHYLLOPOULOS, M.D.,     Senior Research Scientist, The American National Red Cross, Blood Research Laboratory, 9312 Old Georgetown Road, Bethesda, Maryland 20014, USA

EUGENIE TRIANTAPHYLLOPOULOS, M.D., Ph.D.,     Chief Coagulation Research, Department of Hematology, Washington, D. C. 20010, USA

WALTER TROLL, Ph.D.,     Professor Environmental Medicine, New York University School of Medicine, 550 First Avenue, New York, New York 10016, USA

WILLIAM WALKER, MB FRCP (ed),     Physician City Hospital Aberdeen, Scotland Clinical Lecturer in Medicine University of Aberdeen, City Hospital, Urquhart Road Aberdeen, Scotland

STANFORD WESSLER, M.D.,     Professor of Medicine, Washington University School of Medicine, Physician-in-Chief, The Jewish Hospital of St. Louis, 216 South Kings Highway, St. Louis, Missouri 63110, USA

CHAPTER 1

Physiology and Biochemistry of Blood Coagulation

EBERHARD F. MAMMEN

Publisher Summary

This chapter discusses the physiology and biochemistry of blood coagulation. Blood coagulation is an important part of hemostasis in the mammalian system. Hemostasis is accomplished by the harmonious interplay of the blood vessel walls with some cellular elements of the blood, especially the platelets, and some of the plasma proteins. The vessel walls contract at and near the site of injury, while the blood platelets adhere and aggregate at this site. The initial adhesion and aggregation of the platelets leads to the formation of a first hemostatic plug. Lower forms of life use local vasoconstriction and cell aggregation as the only means of hemostasis. However, most vertebrates have one more safety factor added to their mechanism of hemostasis. This is the solidification of the blood plasma by the activation of the blood coagulation mechanism. The fluid plasma is transformed to a gel by the conversion of fibrinogen to fibrin. The resulting fibrin clot can be regarded as the second and final hemostatic plug. After fibrin formation, the polymerized fibrin monomers are stabilized by the enzymic action of a fibrin stabilizing factor.

I Introduction

Blood coagulation is an important part of hemostasis in the mammalian system. Hemostasis is accomplished by the harmonious interplay of the blood vessel walls with some cellular elements of the blood, especially the platelets, and some of the plasma proteins (blood coagulation factors). The vessel walls contract at and near the site of injury, while the blood platelets adhere and aggregate at this site. The initial adhesion and aggregation of the platelets leads to the formation of a first hemostatic plug. Lower forms of life use local vasoconstriction and cell aggregation as the only means of hemostasis. However, most vertebrates have one more safety factor added to their mechanism of hemostasis. This is the solidification of the blood plasma by the activation of the blood coagulation mechanism. The fluid plasma is transformed to a gel by the conversion of fibrinogen to fibrin. The resulting fibrin clot can be regarded as the second and final hemostatic plug. After fibrin formation, the polymerized fibrin monomers are stabilized by the enzymic action of a fibrin stabilizing factor (Factor XIII). The crosslinking enzyme has been identified as a transglutaminase (Matacic and Loewy, 1966). Next, the fibrin clot will retract, and in this process of clot retraction platelets are of considerable importance. In the subsequent process of wound healing the fibrin clot is slowly dissolved while fibroblasts grow into the clot.

This chapter will be limited to a description of the physiology and biochemistry of prothrombin activation. The initial phase of the hemostasis mechanism involving platelets is described in Chapter IX, p. 412; the biochemistry and physiology of the fibrinogen to fibrin conversion is covered in Chapter VI, p. 222, and finally the physiology and biochemistry of fibrinolysis is outlined in Chapter VIII, p. 292.

II Historical Aspects of Blood Coagulation

One of the earliest blood coagulation theories was proposed by Morawitz (1904, 1905) and involved the postulated existence of four coagulation factors, fibrinogen, prothrombin, tissue thrombokinase, and calcium ions. These factors were subsequently termed factors I, II, III and IV. Morawitz Morawitz (1905) postulated that prothrombin was converted to thrombin by tissue thrombokinase (thromboplastin) and calcium ions. Thrombin was believed to be the enzyme which converted fibrinogen to fibrin. Already in 1911, Addis accumulated evidence for the existence of another coagulation factor in plasma when he prepared and studied a globulin fraction which would correct the coagulation defect in hemophilic plasma in vitro. Addis assumed that the globulin fraction contained prothrombin, and consequently postulated that hemophilia might be caused by an abnormal prothrombin molecule. This assumption was disputed by Howell (1914) and Howell and Cekade (1926) when they established that prothrombin in hemophilic plasma was normal in quantity and quality. Howell (1914) held the view that hemophilia was caused by a qualitative platelet defect. This assumption was challenged when Feissly and Fried (1924) and Govaertz and Gratia (1931) pointed out that platelet-free normal plasma would correct the coagulation defect in hemophilic blood. Patek and Stetson (1936) then demonstrated that the antihemophilic globulin was not removed from plasma by Berkefeld filtration, and that it could be found in the globulin fraction originally prepared by Addis (1914). Finally, Quick and Stefanini (1948) concluded that normal and hemophilic platelets were equally active. Brinkhous (1939) investigated the delayed thrombin formation in hemophilic plasma and observed that the addition of tissue thromboplastin would normalize thrombin formation. These observations established the existence of yet another blood clotting factor in addition to the factors postulated by Morawitz Morawitz (1905). The factor was subsequently called antihemophilic factor, antihemophilic globulin or factor VIII. Brinkhous’ work provided the early evidence for a pathway in coagulation not involving tissue thromboplastin. This concept had already been introduced by Bordet and Gengou (1901) and Morawitz Morawitz (1905) who independently established that blood may clot in the absence of tissue thromboplastin when brought into contact with glass. These experiments were basic to our present concept of prothrombin activation via two pathways, an extrinsic one, involving tissue thromboplastin, and an intrinsic one, involving only plasma constituents and platelets. Additional coagulation factors, at present believed to be involved in the extrinsic and intrinsic pathways of prothrombin activation, have been recognized mainly, although not entirely, from clinically oriented research work. In 1947, Owren (1947a, b) discovered a patient with a coagulation disturbance which differed from classical hemophilia. The patient had normal prothrombin and fibrinogen levels, but, in contrast to classical hemophilia, the addition of tissue thromboplastin did not correct the clotting abnormality. Owren (1947a, b) called the disease parahemophilia and implied that a hitherto unrecognized coagulation factor necessary for prothrombin activation was absent in the patient’s plasma. Since normal plasma corrected the patient’s abnormal clotting mechanism, the factor was considered to be present in normal plasma. The activity was termed factor V. Soon it became apparent that factor V possessed the same activity as a plasma fraction already recognized in 1938 by Seegers et al. (1938a), later referred to as Ac-globulin by Ware et al. (1947a, b). Quick (1943) had termed this activity labile factor.

The following years were marked by the additional recognition of further prothrombin activation accelerators, such as factor VII also termed serum prothrombin conversion accelerator (SPCA), Proconvertin or stable factor (Alexander et al. 1949a; DeVries et al. 1949; Alexander et al. 1951; Koller et al. 1951, 1952); factor IX also called plasma thromboplastin component (PTC), Christmas factor or antihemophilic factor B (Pavlovsky, 1947; Koller et al. 1950; Aggeler et al. 1952; Biggs et al. 1952; Schulman and Smith, 1952); factor X also known as Stuart factor, Prower factor or Stuart-Prower factor (Telfer et al. 1956; Hougie et al. 1957); factor XI originally described as plasma thromboplastin antecedent (PTA) (Rosenthal et al. 1953); and factor XII also termed Hageman factor (Ratnoff and Colopy, 1955). In most instances, a patient with a bleeding tendency and an impaired prothrombin conversion was observed. When the defect seemed to be different from any one previously recognized, the defect was attributed to the absence of a hitherto unknown coagulation factor. In many instances the patient’s name was attached to the supposedly missing factor. Since normal plasma would correct the patient’s clotting defect, normal plasma was assumed to contain the factor in question. Such reasoning is acceptable as long as it is clearly understood that it is only a working hypothesis. Rather than assuming the complete absence of a factor, the factor may be present in a biochemically modified form. The resulting pathology would be the same in either case. From the hemoglobinopathies it is well recognized that the exchange of one amino acid in the molecular structure of the hemoglobin molecule produces severe functional changes in the molecule. Recently, the same observation has been made in a family with an abnormal fibrinogen molecule (Blombäck et al. 1968, Mammen et al. 1969). The exchange of one amino acid caused an impaired polymerization of the fibrinogen molecules and a severe hemorrhagic tendency. Such abnormalities could underlie other deficiency states, resulting in congenital bleeding disorders, and would be fully compatible with the established pattern of heredity. It also must be kept in mind that the correction of a deficiency plasma by normal plasma does not necessarily imply the existence of a separate clotting factor. The existence of individual clotting factors is ultimately proven by the isolation of the factor from plasma and by appropriate characterization of its properties.

Brinkhous (1959) wrote in his review, Today it is realized generally that detailed chemical studies will be required before hypotheses (which include all coagulation reactions) of lasting value can be developed. Such chemical studies are beginning to appear, but many uncontrolled and at present seemingly uncontrollable variables still plague the investigator. Kline (1965) pointed out that investigators have not been content to wait for detailed chemical studies and have proposed comprehensive blood coagulation schemes. Since his (the investigator’s) hypotheses are not on firm ground, constant revision is the price the imaginative scientist must pay in exchange for exhilerating leaps into the partially known (Kline, 1965). This statement indeed finds its reflection in the number of coagulation schemes proposed in the last 15–20 years. Obviously, it will not be possible to discuss all of them in this chapter. This outline will be limited to a discussion of basically two theories which have emerged over the last few years to explain the events leading to the activation of prothrombin.

The first theory is the cascade or waterfall hypothesis of prothrombin activation originally proposed by Davie and Ratnoff (1964) and by Macfarlane (1964a). It was subsequently reviewed and expanded by Macfarlane (1965, 1966) and Davie and Ratnoff (1965). This hypothesis states that all clotting factors are distinct entities in plasma, synthesized independently, and present in plasma as inactive precursors. Each coagulation factor is activated by the preceeding one in a chain of events that ultimately leads to the conversion of prothrombin to thrombin. Inherited coagulopathies are believed to be due to absence of specific coagulation factors.

The second concept of prothrombin activation has been proposed over the last 20 years by Seegers and his associates and is found in a number of books and review articles (Seegers, 1962; 1964; 1965; 1967; 1968; 1969; Seegers et al. 1967a; Mammen, 1968). Seegers’ basic approach to blood coagulation consists of the purification and biochemical characterization of the coagulation constituents in question and of a study of the kinetics of their interaction. Seegers was the first to purify prothrombin from plasma (Seegers et al. 1938b; Seegers, 1940; Seegers and Smith, 1941; Seegers, 1952; Ware and Seegers, 1948a). He placed the original concept of blood coagulation proposed by Morawitz Morawitz (1905) on a firm basis. His studies of the prothrombin molecule suggested that prothrombin may be a multifunctional entity that not only can be converted into thrombin, but which can also dissociate to produce other derivates, termed autoprothrombins.

At a superficial glance these two theories seem to have very little in common. This would mean that prothrombin is activated in one way for one group of investigators and in another way for another group. Obviously, there is only one way, in vivo. Assuming that the immense number of experiments performed by the supporters of both theories are correct, there must be some kind of a common denominator that ultimately indicates the most likely mechanism by which prothrombin is activated. In this review, an attempt will be made to correlate both concepts. It will not be possible to cite each one of the several thousand articles that have been written on this subject but an attempt will be made to highlight the most important contributions. Therefore, the bibliography will be selective rather than complete.

III Nomenclature

A serious problem in understanding blood coagulation has been and still is, to a certain extent, the conflicting nomenclature used for the description of the various coagulation constitutents. This has rendered communication difficult among experienced research workers in the field. The uninitiated investigator who starts working in this area is especially handicapped by this state of semantic confusion. The confusion commenced when different names were employed for the same activity, and when identical names were used for different activities. Part of this is due to the almost simultaneous discovery of similar bleeding disorders in different laboratories, as discussed in the historical outline above. An International Committee on Blood Clotting Factors was formed in 1954 and given the task to design a common symbolic language for the unequivocal identification of blood coagulation factors. The Committee has met almost annually and Roman numerals have been assigned to activities, the absence of which results in clinical abnormalities of blood coagulation. The reports of the Committee, published since 1959 as Supplements to Thrombosis et Diathesis Haemorrhagica, include some biochemical and physicochemical properties of preparations containing the activity in question, but it must be recognized that the chemical identity of a number of these activities remains uncertain.

In the symbolic description established by the nomenclature committee, a Roman Numeral refers to the inactive precursor state of the clotting factor in question; the corresponding active form of the clotting factor is denoted by the Roman Numeral followed by the letter a. Since numerals in themselves are principally meaningless, a table is composed (Table 1) in which the Roman Numerals are correlated with the most common synonyms that are or were used in the literature.

Table 1

*Most likely activated Factor X

IV Physicochemical Properties of Coagulation Constituents

In recent years, it has become increasingly evident that biochemical procedures have to be applied to the study of blood coagulation in order to better understand this physiological mechanism. In biochemistry, a first order requirement is the isolation of the substance in question in the purest possible form. Once isolated, the component can be characterized in terms of its structure and function. This approach has been difficult in the case of a number of coagulation constituents because of the inherent lability of these components. In spite of these difficulties, a number of coagulation factors have been purified and characterized to a certain extent. In the following, we will examine the physical-chemical properties of coagulation constitutents involved in prothrombin activation. Procedures for the purification of individual factors are found in Chapter IV.

A Prothrombin

Prothrombin was one of the earliest coagulation proteins isolated from bovine plasma, in the pioneering work of Seegers and his associates (Seegers et al. 1938b; Seegers, 1940; Seegers and Smith, 1941; Seegers et al. 1945a; Ware and Seegers, 1948a; Seegers, 1952; 1962). Other procedures for the isolation of bovine prothrombin have been described by Goldstein et al. (1959), Moore et al. (1965) and Tishkoff et al. (1968). Prothrombin from human plasma has been isolated by a number of investigators (Lanchantin et al. 1963; Lanchantin and Friedmann, 1963; Magnusson, 1965a; Shapiro and Waugh, 1966; Aronson (1966).

Plasma of other animal species has also been the source of purified prothrombin. These procedures include those of Anderson and Barnhart (1964) for the isolation of canine prothrombin, the method of Miller and Phelan (1967) and Miller and McGarrahan (1958) for the purification of equine prothrombin, and the procedure of Li and Olson (1967) for the preparation of purified rat prothrombin. The preparations from the various animal plasmas vary considerably in their activity and purity. Probably the best prothrombin preparations have been obtained from bovine plasma; consequently, most of the physico-chemical studies have been performed on bovine prothrombin. According to available comparative studies, bovine and human prothrombin are similar in most respects (Lanchantin et al. 1968a, b).

The concentration of prothrombin in bovine plasma was found to be 0.1–0.15 mg/ml (Seegers, 1962); it may be lower in the human. In both bovine and human plasma the prothrombin activity migrated electrophoretically with the α2-globulin fraction (Owen and McKenzie, 1954; Seegers, 1962). Purified bovine prothrombin preparations migrated in the area of the α1-globulins (Seegers et al. 1950). Purified human prothrombin had the mobility of an α2-globulin. By means of moving boundary electrophoresis bovine prothrombin complex had an isoelectric point of pH 4.25 in a buffer of ionic strength 0.2 (Seegers et al. 1966a); in buffers of ionic strength 0.1 an isoelectric point of pH 4.1 was found (Tishkoff et al. 1968).

Purified bovine prothrombin preparations with a specific activity of 2,200 Iowa units/mg protein were homogeneous in the analytical ultra-centrifuge. In free electrophoresis experiments, the same products also displayed a single symmetrical peak at pH’s below 7.0; above pH 7.0 the prothrombin tended to dissociate (Seegers et al. 1966a). Despite the apparent physical homogeneity, these prothrombin preparations contain factor X, VII and IX activities. These activities can be removed by chromatography on DEAE-cellulose. In the following, the chromatographed prothrombin preparations will be referred to as prothrombin or DEAE-prothrombin, while the non-chromatographed preparations will be termed prothrombin complex. The sedimentation rate for bovine prothrombin complex (S°20,w) was 5.22 Svedberg units (Harmison et al. 1961), the partial specific volume (v¯) was 0.70ml/gm, and the diffusion coefficient (D20,w) was 6.25×10−7 cm²/sec (Lamy and Waugh, 1953). From these biophysical measurements, a molecular weight of 68,000 to 68,500 has been calculated (Lamy and Waugh, 1958; Harmison et al. 1961). Using sedimentation equilibrium analysis a molecular weight of 70,500 was obtained for bovine prothrombin complex (Tishkoff et al. 1968). Molecular weight determinations on thin-layer gel filtration gave an average value of 68,000±4,000 (Murano, 1968). The sedimentation constant for DEAE-prothrombin was also 5.3 S (Seegers et al. 1969). The molecular weight by physical analysis, as reported by Tishkoff et al. (1968), was 65,500± 1,247. Murano (1968) found by thin-layer gel filtration a molecular weight of 66,500 ± 3,000. The molecular weight of human prothrombin was reported as 68,700 (Lanchantin et al. 1968a). Equine prothrombin complex had a sedimentation coefficient of 5.35 Svedberg units, a diffusion coefficient of 3.8 × 10−7 cm²/sec, and a molecular weight of about 130,000 (Miller and McGarrahan, 1958). It is apparently twice as large as bovine prothrombin complex.

The bovine prothrombin complex possessed the apparent shape of an ellipsoid with a length of 119 Å and a width of 34 Å (Lamy and Waugh, 1953) when calculated by the method of Flory and Fox (1950), and a length of 134 Å and width of 35 Å when calculated on the basis of its molecular weight (Harmison et al. 1961). In the electron microscope, prothrombin complex displayed a rather uniform globular appearance with a height of 105 Å (Riddle et al. 1963). Allowing for loss of internal hydration, these dimensions would agree with the values derived from studies of its hydrodynamic behaviour.

The amino acid composition of the bovine prothrombin complex has been determined by several investigators (Laki et al. 1954; Magnusson, 1965b; Seegers et al. 1967b). All values are in fair agreement and the most recent one (Seegers et al. 1967b), is listed in Table 2. The prothrombin complex contained 526 amino acid residues. This value may not represent the accurate number of residues in prothrombin, since the prothrombin complex contains variable quantities of factors X, VII and IX. Using the procedure of Brand (1946), a molecular weight of 58,800 has been calculated on the basis of the amino acid composition (Seegers et al. 1967b). This value is slightly below the one previously calculated on the basis of a different amino acid composition (Harmison and Mammen, 1967). If allowance was made for the carbohydrate content of prothrombin complex, a carbohydrate weight of approximately 8,000 had to be added to the molecular weight based on the amino acid composition. The molecular weight for the entire glycoprotein would then be about 66,800 which is in close approximation with the molecular weight calculated from biophysical measurements. Seegers et al. (1969) determined the amino acid composition of prothrombin chromatographed on DEAE cellulose (Table 2).

Table 2

Amino Acid Composition

¹Seegers et al. (1967b)

²Lanchantin et al. (1968a)

³Seegers et al. (1969)

⁴Seegers et al. (1967b)

⁵Seegers et al. (1967b)

⁶Seegers et al. (1968)

⁷Seegers et al. (1968)

The amino acid composition of human prothrombin (Table 2) is similar to that of bovine prothrombin, with the exception of the values for threonine and tryptophan. A total of 556–559 amino acid residues were found for the protein moiety of human prothrombin (Lanchantin et al. 1968a).

In 8 molar urea solution, 8 moles of disulfide were found per mole of bovine prothrombin complex (Carter and Warner, 1954, 1956).

The terminal amino acids of prothrombin complex have been studied by several investigators and the N-terminal amino acid is alanine (Magnusson, 1958; 1965b; Miller, 1958; Thomas and Seegers, 1960; Murano, 1968). Prothrombins prepared by a variety of different procedures had identical N-terminal residues. Two C-terminal amino acids, tyrosine and glycine, were found in non-chromatographed and on IRC-50 chromatographed bovine prothrombin complex (Thomas and Seegers, 1960) using the ammonium thiocyanate method (Tibbs, 1951). With the carboxypeptidase method no C-terminal amino acids could be determined (Miller and Van Vunakis, 1956a; Magnusson and Steele, 1965). Apparently, the C-terminal residues of prothrombin are not available for carboxypeptidase action (Magnusson, 1965c).

The total carbohydrate content of bovine prothrombin complex was 11.2 % (Schwick and Schultze, 1959), respectively 11.6 % (Magnusson, 1965d). Galactose, mannose and fucose were 3.06, 1.53, and 0.09 %, respectively; hexosamine was 2.3 % and sialic acid was 4.2 % (Schwick and Schultze, 1959; Magnusson, 1965b). Tishkoff et al. (1968) reported similar values. The total carbohydrate content of human prothrombin was found to be around 10 % (Lanchantin et al. 1968a).

From the empirical data it is apparent that prothrombin complex and DEAE-prothrombin are very similar. This indicates that the associated activities (factors X, VII and IX) in the prothrombin complex constitute such a slight contamination as to not influence physical measurements.

B Prethrombin

When prothrombin complex is converted to thrombin, a dissociation of the complex takes place which precedes the actual development of thrombin activity (Lorand et al. 1953; Seegers and Alkjaersig, 1956). This dissociation has been observed in the analytical ultracentrifuge (Lamy and Waugh, 1954; 1958), in moving boundary electrophoresis (Seegers et al. 1950), and by N-terminal amino acid determinations (Magnusson, 1958, 1964; Murano, 1968). At the time of dissociation, 60–80 % of the carbohydrate and approximately 40 % of the protein became soluble in trichloroacetic acid (Lorand et al. 1953; Seegers and Alkjaersig, 1956). Since at the time of dissociation no thrombin activity could be measured, it had to be assumed that thrombin was present in an inactive fragment which had to be different from the original prothrombin. This fragment has been isolated in purified form and was termed prethrombin (Seegers and Marciniak, 1965; Marciniak and Seegers, 1965; Seegers et al. 1965a; 1967b). Similar inert degradation products of bovine and human prothrombin have been described and studied by other investigators (Asada et al. 1961; Magnusson, 1965f; Lanchantin et al. 1965a; 1967; 1968b; Aronson, 1966; Aronson and Menache, 1966; Tishkoff et al. 1968).

In contrast to prothrombin, prethrombin could neither be converted to thrombin in 25 % sodium citrate solution (Seegers et al. 1967b) nor by tissue thromboplastin under the conditions of the two-stage analytical procedure, described by Ware and Seegers (1949) (Seegers and Marciniak, 1965). Only when autoprothrombin C (activated factor X) was added, thrombin would form from prethrombin. Basically, autoprothrombin C alone activated the substrate (Seegers and Marciniak, 1965; Marciniak and Seegers, 1966a; 1966b; Seegers et al. 1967b). Prethrombin, in contrast to prothrombin, could not be activated in the presence of platelet factor 3 and factor VIII (Marciniak and Seegers, 1966a). While purified prothrombin complex readily corrected the clotting defect of factor VII, IX and X deficient plasmas, purified prethrombin was inactive in this respect (Marciniak and Seegers, 1965; 1966a).

Prethrombin has been isolated from purified bovine prothrombin complex which had been dissociated with thrombin at pH 7.0 (Seegers and Marciniak, 1965; Marciniak and Seegers, 1965; Seegers et al. 1967b). The actual procedure is described in Chapter IV. When assayed with a modified two-stage analytical procedure (Marciniak and Seegers, 1965), specific activities as high as 40,000–45,000 Iowa units/mg tyrosine were obtained. These activities are near the specific activity of purified thrombin (Seegers et al. 1958).

In the analytical ultracentrifuge and by cellulose acetate electrophoresis, purified prethrombin displayed homogeneity (Seegers et al. 1967b). A sedimentation coefficient (S⁰20,w) of 3.93 Svedberg units was found. The regression line relating sedimentation rate to concentration had a small positive slope (Seegers et al. 1967b). It resembled in this respect, to a certain extent, the positive slope obtained with thrombin. The sedimentation coefficient of prethrombin was smaller than that of prothrombin, but still larger than that of thrombin (3.76 Svedberg units). Diffusion coefficient and partial specific volume have not been determined for prethrombin so that no molecular weight has been calculated on the basis of physical measurements. On the basis of thin-layer gel filtration, prethrombin had a molecular weight of 52,000 ± 9,000 (Murano, 1968). Tishkoff et al. (1968) used sedimentation equilibrium centrifugation and found a molecular weight of 52,395 ±3,449 for their modified zymogen which is apparently identical with prethrombin.

The isoelectric point of prethrombin in acetate buffer of ionic strength 0.1 was pH 5.5 (Seegers et al. 1967b) which again is markedly different from prothrombin complex (pH 4.1), but only slightly different from thrombin (pH 5.75).

The amino acid composition of prethrombin was determined by Seegers et al. (1967b) and is listed in Table 2.

The N-terminal amino acids were determined by Murano (1968). Prethrombin had two N-terminal amino acids, lysine and threonine. The average recovery of lysine was 1.03 M/52,000 gm, the average recovery of threonine 0.97 M/52,000 gm.

These findings place the prethrombin fragment as an intermediate between prothrombin and thrombin. Based on molecular weight, prethrombin is smaller than prothrombin but still larger than thrombin. Prothrombin has 1 mole N-terminal alanine per 65,000 to 70,000 gm, indicating that it is a single chain molecule. Prethrombin has two N-terminal amino acids, lysine and threonine (1 mole of each per 52,000 gm), indicating that it is a two-chain molecule. These findings indicate that the activation of prothrombin to prethrombin by thrombin involves the N-terminal end of the prothrombin molecule; apparently a peptide containing the alanine N-terminal portion in prothrombin is cleaved and discarded. However, one additional cleavage point must occur in order to form a two-chain molecule from a one-chain molecule. This cleavage most likely occurs between an intra-chain disulfide bridge. Thereby, prethrombin becomes a two-chain molecule, like thrombin. Moreover, one of the N-terminal amino acids (threonine) is the same as in thrombin. However, the active site of the thrombin molecule must still be masked in prethrombin since prethrombin possesses no proteolytic activity against fibrinogen. The conversion of prethrombin to thrombin with generation of proteolytic activity can not be achieved by thrombin. Autoprothrombin C (activated factor X, thrombokinase) is necessary for this final activation.

C Thrombin

Thrombin can be obtained by activating purified prothrombin or prothrombin complex in different ways, and again a number of investigators have attempted its isolation () was 0.69 ml/gm (Harmison et al. 1961). From these biophysical measurements a molecular weight of 33,700 was calculated (Harmison et al. 1961). This value is in agreement with figures described by Magnusson (1965e) and by Baughman and Waugh (1967), obtained by different methods. When the molecular weight was calculated on the basis of specific activitites, a value of 33,600 was obtained (Harmison et al. 1961). Using thin-layer gel filtration Murano (1968) determined a molecular weight of 32,000 ± 2,500 for bovine thrombin. Lanchantin et al. (1965a) estimated the molecular weight of human thrombin, using exclusion chromatography on Sephadex G-100 and found a value of 35,000. On the basis of kinetic studies, Kezdy et al. (1965) calculated a maximal value of 32,600, while Magnusson (1965e) found on the basis of the N-terminal amino acid content a molecular weight of 26,000 to 32,000 for human thrombin. Miller et al. (1965) reported a value of 26,200. Based on its hydrodynamic characteristics the length of the bovine thrombin molecule was calculated with 84 Å, the width being 30 Å (Harmison et al. 1961). This is in fair agreement with measurements obtained by electron microscopy, where the mean particle height was measured at 91 to 92 A (Riddle et al. 1963). The particles displayed remarkable homogeneity.

The isoelectric point of bovine thrombin was calculated at pH 5.6 when measured by paper electrophoresis (Levine and Neuhaus, 1959) and pH 5.75 when determined by moving boundary electrophoresis (Seegers et al. 1966a). The amino acid composition of bovine thrombin has been determined by several investigators (Miller et al. 1959; Schrier et al. 1962; Laki and Gladner, 1964; Seegers et al. 1967b) and remarkable agreement was obtained. The latest reported amino acid composition (Seegers et al. 1967b) is listed in Table 2. The 3.7 S thrombin molecule very likely contains 258 amino acid residues.

The molecular weight based on the amino acid composition using the method of Brand (1946) was found to be 28,400 (Seegers et al. 1969). Correcting this figure for the carbohydrate content of bovine thrombin gives a value which is in good agreement with the molecular weight calculated from physical measurements and specific activities.

Carter and Warner (1956) titrated 2.15 moles of disulfide per mole of thrombin. On the basis of the amino acid composition 3 moles per mole have to be assumed.

The bovine thrombin molecule had 2 N-terminal amino acids, isoleucine and threonine (Magnusson, 1965c; Murano, 1968). One mole of each was found per 33,000 gm (Murano, 1968). This indicates that thrombin is a two-chain molecule. Magnusson (1968) has identified an A-chain and a B-chain in bovine thrombin, held together through disulfide linkage. The N-terminal amino acid of the A-chain was threonine. The chain consisted of 49 amino acids. The N-terminal amino acid of the B-chain was isoleucine and at present the sequence of the first four amino acids of this chain has been reported (Magnusson, 1965e). These were Ileu-Val-Glu-Gly. For human thrombin this sequence was Ileu-Val-Gly-Gly (Magnusson, 1965e).

The total carbohydrate content of thrombin has been estimated at 9.68 % (Schwick and Schultze, 1959), with 2.34 % galactose, 1.17 % mannose, 0.07 % fucose, 2.2 % hexosamine and 3.9 % sialic acid.

Thrombin is a proteolytic enzyme that introduces the conversion of fibrinogen to fibrin by splitting arginyl-glycyl bonds at the N-terminal end of the fibrinogen molecule. Details of this action are outlined in Chapter VI, p. 224. Thrombin, furthermore, dissociates prothrombin to yield prethrombin, autoprothrombin III and an inhibitor (Marciniak and Seegers, 1965; Seegers and Marciniak, 1965; Seegers et al. 1967a; Seegers, 1968, 1969).

The esterolytic activity of thrombin was first described by Sherry and Troll (1954), and a pronounced effect was noted on tosyl-L-arginine methyl ester (TAMe). In addition to TAMe, benzoylarginine methyl ester (BAMe), tosyl-L-lysine methyl ester (TLMe), benzoylarginine-p-nitroanilide, and other acyl- and peptidyl-arginyl amides, as well as certain betanaphthylamides are split (Sherry and Troll, 1954; Ehrenpreis et al. 1957; Ronwin, 1959; Martin et al. 1959; Lorand et al. 1962; Ratnoff, 1962; Deutsch et al. 1962; Elmore and Curragh, 1963; Lanchantin et al. 1965b; Magnusson, 1965c). Apparently, acytelated arginine and lysine esters are rapidly hydrolized by thrombin, whereas tosyl substrates with glycine and tyrosine are not split (Sherry et al. 1954).

By acetylation of thrombin with acetic anhydride most of the clotting power of the enzyme was destroyed. However, the esterolytic activity was maintained (Landaburu and Seegers, 1959). This esterase-thrombin or thrombin-E has been isolated, it was homogeneous in the ultracentrifuge, and had a sedimentation coefficient of 3.2 Svedberg units (Seegers et al. 1960a). The infusion of esterase-thrombin in dogs resulted in an activation of the fibrinolytic system (Seegers et al. 1960b; Seegers, 1961). The fibrinolytic action of thrombin had already been noted previously (Nolf, 1908; Guest and Ware, 1950).

Active center studies on thrombin have revealed that DFP (Diisopropylfluorophosphate) destroyed the clotting and esterolytic activity of the enzyme (Gladner and Laki, 1956; Miller and Van Vanukis, 1956b). Since DFP combines with a single serine amino acid residue (Gladner and Laki, 1958) it can be assumed that serine constitutes a part of the active center of the thrombin molecule. The thrombin activity was also inhibited by 1-chloro-3-tosylamido-7-amino-2-heptanone (TLCK) (Shaw et al. 1965; Marciniak and Seegers, 1966a), indicating that histidine is also a part of the active center of thrombin. TPCK (tosylphenylalanine chloromethyl ketone) did not inhibit thrombin activity (Seegers et al. 1965b). In contrast to this, phenylmethanesulfonyl fluoride (PMSF) destroyed thrombin activity (Seegers et al. 1965b). Also oxidizing agents, especially potassium permanganate, and amino group reagents, such as S-acetyl mercaptosuccinic anhydride and formaldehyde, inhibited the activity of thrombin (Caldwell and Seegers, 1965).

Recently, Seegers et al. (1968) rechromatographed 3.76 S thrombin on Amberlite IRC-50 and thereby raised the specific activity from about 4,200 U/mg protein to 8,200 U/mg protein. This compares favorably with the high specific activities found for human thrombin (Miller and Copeland, 1962, 1965). In the analytical ultracentrifuge this rechromatographed thrombin had a sedimentation coefficient of 3.2 S Svedberg units (Seegers et al. 1968) with the usual negative slope, when protein concentration was plotted against sedimentation rate. The amino acid composition of this thrombin is listed in Table 2. Upon calculation, it becomes apparent that 75 amino acid residues have been removed from the 3.76 S thrombin. The total number of residues (predominantly glutamic and aspartic acid) for the 3.2 S thrombin was 183, instead of 258 for the 3.76 S thrombin. Cystine and tryptophan residues remained unchanged. This seems to indicate that acidic peptides were removed which normally adhered to the 3.76 S thrombin (Seegers et al. 1968). The removal of these peptides resulted in a shift of the isoelectric point from pH 5.75 for the 3.76 S thrombin to pH 6.2 for the 3.2 S thrombin (phosphate buffer, ionic strength 0.1).

Based on the amino acid composition, a molecular weight of 21,100 was calculated for the protein moiety (Seegers et al. 1969). Corrected for the carbohydrate content, the 3.2 S thrombin had a molecular weight of 22,800 (Seegers et al. 1968). Using thin-layer gel filtration Murano (1968) found a molecular weight of 23,000±1,000.

The orcinol reactive carbohydrate content of the 3.2 S thrombin was 5.02 %, with 1.7 % sialic acid, 0.69 % glucosamine and 0.46 % galactosamine (Seegers et al. 1968).

The N-terminal amino acids of rechromatographed thrombin (3.2 S) were also threonine and isoleucine in a ratio of 1 mole of each per 23,000 gm (Seegers et al. 1968; Murano, 1968). In this respect, they are not different from the 3.76 S thrombin. Therefore, one can assume that the 75 amino acid residues were not removed from the N-terminal end of the molecule.

Since the removal of the 75 amino acid residues (29 % of the total protein) resulted in a doubling of the specific activity, one must assume that the acidic peptides had inhibitory properties (Seegers et al. 1968). This interpretation would be consistent with the findings of Landaburu et al. (1965) who found inhibitory material associated with the 3.76 S thrombin. When 3.2 S thrombin was acetylated with acetic anhydride, as described by Landaburu and Seegers (1959), the clotting activity was reduced to less than 1 %, but no change was observed in the sedimentation coefficient (Seegers et al. 1968). When 3.76 S thrombin was acetylated, the sedimentation constant was reduced to 3.2 Svedberg units (Seegers et al. 1960a). Upon determination of the amino acid composition of the acetylated 3.76 S thrombin and the acetylated 3.2 S thrombin (Table 2) it became apparent that both acetylated thrombins exhibited identical amino acid compositions (Seegers et al. 1968). Moreover, the amino acid composition of the acetylated 3.76 S thrombin and the acetylated 3.2 S thrombin was, within the limits of error, identical with the one of non-acetylated 3.2 S thrombin (Seegers et al. 1968). It appears that the identical 75 amino acids residues were removed by acetylation of the 3.76 S thrombin and by rechromatography on Amberlite IRC-50. In the latter procedure, however, the clotting power is retained.

Seegers et al. (1968) determined the Michaelis Constant for these three types of thrombin, using p-toluenesulfonyl-L-arginine methyl ester (TAMe) as substrate. They found Km = 2.97 × 10−4 M for 3.76 S thrombin, Km = 9.5×10−5 M for 3.2 S thrombin and Km = 4.85× 10−4 M for acetylated 3.76 S thrombin.

The physical-chemical data at present available for thrombin clearly indicate that thrombin has about half the molecular weight of prothrombin. These findings have led Seegers and coworkers to hypothesize that the other half of the prothrombin might be composed of autoprothrombin III (inactive factor X). In view of more recent findings which will be discussed later, this hypothesis can no longer be upheld. Newer investigations by Murano (1968) and Seegers et al. (1968) seem to open the possibility that prothrombin might be a dimer of two thrombin molecules. This interesting assumption is at present under investigation.

D Factor X

Morawitz Morawitz (1905) observed that blood, carefully collected without contamination with tissue material, would yield thrombokinase when brought into contact with glass. This thrombokinase was thought to activate prothrombin to thrombin. It was believed to have similar properties to thrombokinase from tissues. Mellanby (1909) indicated that a prothrombin activator could be obtained from plasma globulins. In 1912, Collingwood and McMahon suggested that thrombokinase existed in an inactive form in blood and suggested that this precursor of thrombokinase comes from platelets. The authors termed this precursor prothrombokinase. Subsequently, Dale and Walpole (1916) established that thrombokinase comes from plasma and not from platelets. Several years later Lenggenhager (1936, 1940) and Widenbauer and Reichel (1942) supported the concept that thrombokinase is present in plasma in an inactive precursor form. Milstone (1942, 1947, 1948, 1949, 1951, 1952a, 1952b, 1952c, 1955, 1959a, 1959b) confirmed that thrombokinase is the activator of prothrombin; he isolated thrombokinase from plasma (Milstone, 1960a, 1960b) and gave an elaborate description of its functional properties (Milstone, 1962, 1964; Milstone et al. 1963).

In 1953, Biggs et al. (1953a) indicated that blood contained all of the components necessary for blood or intrinsic thromboplastin formation, and described a test system which measured the rate of plasma thromboplastin formation (Biggs and Douglas, 1953). This test is the so-called plasma thromboplastin generation test. Biggs et al. (1953b, 1953c) suggested that the formation of thromboplastin may progress in a stepwise fashion.

In 1956, Bergsagel and Hougie (1956) reported that the incubation of factors VIII, IX and X together with calcium ions results in the formation of a powerful procoagulant which together with factor V and platelets forms blood thromboplastin. They termed this procoagulant product I. Subsequently, product I was partially purified and its functional properties investigated (Bergsagel, 1956; Zucker-Franklin et al. 1961, Spaet and Cintron 1959, 1960, 1961, 1963; Horowitz and Spaet, 1961, Spaet, 1962, 1964).

Further interest in factor X was generated when Telfer et al. (1956), Hougie (1956) and Hougie et al. (1957) described patients with a bleeding disorder and impaired prothrombin activation. This disease was closely related to the so-called factor VII deficiency previously described by Alexander et al. (1949a, 1951), De Vries et al. (1949) and Koller et al. (1951, 1952). The new disease was later called Stuart-Prower factor deficiency or factor X deficiency. Several years later, Macfarlane (1961) and Esnouf and Williams (1961) presented evidence that factor X was the substrate for the clotting action of Russel’s Viper Venom, and Esnouf and Williams (1962a) studied this interaction after purifying the venom. At the same time, they isolated the substrate (factor X) from plasma and serum and described some of its physicochemical properties (Esnouf and Williams, 1962b, 1962c).

During the same year, Marciniak and Seegers (1962) discovered that besides thrombin, a second enzyme would form when prothrombin complex, prepared by the method of Seegers (1952), was activated in 25 % sodium citrate solution. They referred to this enzyme as autoprothrombin G, and hypothesized that the enzyme might be a part of the prothrombin molecule and not an independent plasma protein. The term autoprothrombin C had been introduced by Kowarzyk and Marciniak (1961) and Marciniak (1961) when it was noted that thrombin products differed in their ability to promote prothrombin consumption in hemophilic plasma. Autoprothrombin C was subsequently isolated (Seegers et al. 1963a, 1966b) and its functional and physicochemical properties have been described in detail (Seegers and Marciniak, 1962a, 1962b; Seegers et al. 1962a, 1962b, 1962c, 1963a, 1963b, 1963c, 1965a, 1965b, 1966b, 1967a, 1967b; Marciniak et al. 1962a, 1962b, 1962c; Seegers, 1964, 1965, 1967, 1968; Gole et al. 1962; Seegers and Kagami, 1964; Caldwell and Seegers, 1965; Marciniak and Seegers, 1965; Harmison and Mammen, 1967).

The inactive precursor of autoprothrombin C was termed autoprothrombin III when conditions were found where purified prothrombin complex could be activated without generating autoprothrombin C activity (Seegers et al. 1962a, 1964b). Autoprothrombin III has also been isolated and some of its properties have been described (Seegers et al. 1964b, 1967a, 1967b; Seegers and Marciniak, 1965; Harmison and Mammen, 1967; Seegers, 1964, 1965, 1967, 1968).

It is now apparent that autoprothrombin C, activated factor X, thrombokinase and intermediate coagulation product I are one and the same substance (Spaet, 1964, Kline, 1965; Lechner and Deutsch, 1965; Marciniak and Seegers, 1965; Seegers, 1967, 1968; Harmison and Mammen, 1967). It follows then that autoprothrombin III and inactive factor X are also identical entities.

1 Molecular Characteristics of Inactive Factor X

Inactive factor X (autoprothrombin III) has been isolated from bovine plasma (Esnouf and Williams, 1962b); Papahadjopoulos et al. 1964a; Lechner and Deutsch, 1965) and from purified prothrombin complex preparations (Seegers et al. 1964b; Seegers and Marciniak, 1965; Lechner and Deutsch, 1965). Details of the procedure are described in Chapter IV, p. 151. In cellulose acetate electrophoresis purified factor X samples from plasma migrated in the area of the α1-globulins (Papahadjopoulos et al. 1964a). The electrophoretic mobility in 0.08 M NaCl buffered with 0.01 M tris: HCl buffer was 7.26×10−5 cm²/V/sec (Esnouf, 1965). The isoelectric point of autoprothrombin III in either phosphate or acetate buffer at 0.1 ionic strength was found to be pH 4.75 (Seegers et al. 1967b).

Esnouf and Williams (1962b, 1962c) obtained for their factor X preparation a sedimentation coefficient (S°20,w) of 4.23 Svedberg units, a diffusion coefficient (D20) of 4.57 × 10−7 cm²/sec and a partial specific volume (v¯) of 0.738. On the basis of these data a molecular weight of 87,000 was calculated. Ultracentrifuge analysis revealed a molecular weight of 84,800 ± 7,000. Autoprothrombin III had a sedimentation coefficient (S°20,w) of 3.4 Svedberg units (Seegers et al. 1967b), a figure which is lower than that obtained by Esnouf and Williams (1962b). However, diffusion coefficient and partial specific volume have not as yet been determined for autoprothrombin III, and hence no molecular weight estimates have been feasable. Murano (1968) using thin-layer gel filtration, estimated a molecular weight of 74,000 ± 9,000 for autoprothrombin III. Jackson and Hanahan (1968) described a molecular weight of 55,000 for