In one generation, the numerous factors involved in blood coagulation have become real protein entities, isolated in pure form, expressed by recombinant DNA techniques, and subjected to structure elucidation by the modem methods of physical chemistry, viz. , X-ray diffraction, and NMR, ESR and fluorescence spectroscopy. The major milestone in this field was the breakthrough achieved by W. Bode, R. Huber and their colleagues in 1989 in of human a-thrombin, inhibited with D-Phe-Pro-Arg determining the crystal structure chioromethyl ketone. The availability of this structure will greatly facilitate the interpretation of experiments designed to gain an understanding of the interatomic interactions between this enzyme and fibrinogen and its other substrates. At the same time, it provides a rational basis for the design and synthesis of inhibitors of thrombin, the subject of this symposium. The symposium was organized in four sessions: (1) Structural features of the interaction of thrombin with substrates and inhibitors, (2) Synthetic inhibitors, (3) Hirudin and its analogues, and (4) Pharmacological and clinical considerations. This book contains summaries of most of the papers presented, and takes its rigbful place among two others that provide a comprehensive picture of our current knowledge about thrombin, viz. the 1977 volume entitled "Chemistry and Biology of Thrombin", edited by R. L. Lundblad, J. W. Fenton II, and K. G. Mann, and the 1992 volume entitled "Thrombin: Structure and Function", edited by L. J. Berliner.

In one generation, the numerous factors involved in blood coagulation have become real protein entities, isolated in pure form, expressed by recombinant DNA techniques, and subjected to structure elucidation by the modem methods of physical chemistry, viz. , X-ray diffraction, and NMR, ESR and fluorescence spectroscopy. The major milestone in this field was the breakthrough achieved by W. Bode, R. Huber and their colleagues in 1989 in of human a-thrombin, inhibited with D-Phe-Pro-Arg determining the crystal structure chioromethyl ketone. The availability of this structure will greatly facilitate the interpretation of experiments designed to gain an understanding of the interatomic interactions between this enzyme and fibrinogen and its other substrates. At the same time, it provides a rational basis for the design and synthesis of inhibitors of thrombin, the subject of this symposium. The symposium was organized in four sessions: (1) Structural features of the interaction of thrombin with substrates and inhibitors, (2) Synthetic inhibitors, (3) Hirudin and its analogues, and (4) Pharmacological and clinical considerations. This book contains summaries of most of the papers presented, and takes its rigbful place among two others that provide a comprehensive picture of our current knowledge about thrombin, viz. the 1977 volume entitled "Chemistry and Biology of Thrombin", edited by R. L. Lundblad, J. W. Fenton II, and K. G. Mann, and the 1992 volume entitled "Thrombin: Structure and Function", edited by L. J. Berliner.

Recent years have seen tremendous advances in our understanding of the molecular mechanism of platelet activation. All aspects of signal transduction in platelets from the identification of surface receptors, G proteins, phospholipases, protein kinases and phosphatases, intracellular receptors for inositol phosphates, the Ca2+ regulatory machinery, cytoskeletal constituents to the control mechanism employing cyclic nucleotides has seen an explosion of information regarding their importance and for each constituent in the family of molecules to which they belong. This information has been of interest to researchers across a wide spectrum of disciplines including biochemists, pharmacologists, cell biologists and clinicians. In April 1992 an International Symposium bearing the name of this volume was organised at the Thrombosis Research Institute to bring together scientists from across the world whose common interest was the study of platelet activation and its regulation. We were particularly encouraged by the positive response from our speakers and the participants, their detailed contributions and the very lively discussions that took place throughout the two days of the symposium. Almost every aspect of signal transduction in human platelets was represented. Of the invited speakers twelve were from Europe (including the U. K. ), eight from North America and one from Japan. This volume is a compilation of chapters submitted by the speakers and represents a concise but informative picture of the present knowledge of the mechanisms of platelet activation and control.