Prothrombin activation with trypsin as enzyme

¹ Department of Physiology and Pharmacology, Wayne State University College of Medicine, Detroit, Michigan

Prothrombin activation with trypsin only involves a random type of proteolysis in which the thrombin yield is small. In the presence of glycerol or certain lipids of interest in blood coagulation and classified as procoagulants, proteolysis of prothrombin with trypsin is made more specific and the thrombin yield is high. The effectiveness of lipids in functioning synergistically with trypsin is, in general, like their procoagulant effect with thrombin. Thus, the clotting factors are seen as catalysts in a proteolytic process, regardless of whether thrombin or trypsin is the enzyme. Trypsin-thrombin was isolated by chromatography on cellulose. Its sedimentation constant in Svedberg units was found to be approximately the same as for other thrombin preparations. Both terminal amino acids were found to be arginine. Most likely trypsin splits a lysine-arginine bond in prothrombin, and also a bond where arginine is attached to an amino group of another amino acid. Acetylated prothrombin was not found to be activated with trypsin. Under appropriate conditions the activation of prothrombin in the presence of trypsin is a zero order reaction.

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				R. H. Landaburu, O. Abdala, and J. Morrone Peptides Attached to Thrombin: Their Influence on Proteolysis Science, April 16, 1965; 148(3668): 380 - 381. [Abstract] [PDF]