Activation of a Pro-Enzyme by a Stoichiometric Reaction With Another Protein. The Reaction Between Prothrombin and Staphylocoagulase

Biochim Biophys Acta. 1975 Jan 30;379(1):180-8. doi: 10.1016/0005-2795(75)90020-3.


The reaction between prothrombin and staphylocoagulase was investigated and the following conclusions were drawn: (a) Optimal amounts of the active reaction product (coagulase-thrombin) are found when equimolar amounts of prothrombin and staphylocoagulase are added together. (b) The molecular weight of coagulase-thrombin equals the sum of the molecular weights of staphylocoagulase and prothrombin when estimated both by gelfiltration and by sodijm dodecylsulphate-polyacrylamide gel electrophoresis. (c) The amino acid composition of coagulase-thrombin cannot be distinguished from the sum of the amino acid compositions of prothrombin and staphylocoagulasd. (d)in a preparation of coagulase-thrombin the N-terminal amino acids are those of prothrombin (alanin) and staphylocoagulase (aspartic acid). (e) An antibody against coagulase-thrombin precipitates prothrombin and staphylocoagulase but not thrombin. (f) We put forward the hypothesis that the thrombin activity in coagulasethrombin is the result of a stoichiometric reaction between one molecule of prothrombin and one molecule of staphylocoagulase, and limited proteolysis does not play a role in this mechanism.

MeSH terms

  • Amino Acids / analysis
  • Blood Coagulation
  • Coagulase / immunology
  • Coagulase / metabolism*
  • Enzyme Activation
  • Enzyme Precursors / metabolism*
  • Esterases / metabolism
  • Molecular Weight
  • Prothrombin / immunology
  • Prothrombin / metabolism*
  • Thrombin / immunology
  • Thrombin / metabolism


  • Amino Acids
  • Coagulase
  • Enzyme Precursors
  • Prothrombin
  • Esterases
  • Thrombin