[Structural bases of thrombin specificity. Role of secondary interactions].
The action of thrombin on the esters, Tos-P2-Arg-OCH3 and Tos-P3-P2-Arg-OCH3, where P2 and P3 are the residues of L-, D- or N-methylamino acids, has been studied. The values of kcat and Km(app) under steady-state conditions at pH 8.5 have been determined. The results obtained and literature data suggest that one of the causes of the low catalytic potency of thrombin is a decrease in the hydrophobicity of the environment of Asp-102 located at the active site of the enzyme. Therefore thrombin can cleave only the peptides which hydrophobically shield Asp-102. The key role in this process may be played by the side chains of the amino acids at P2 and P9, thus suggesting the presence of a beta-turn in the P7-P4 region of the polypeptide substrates of thrombin.
D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009842:Oligopeptides; D011487:Protein Conformation; D013379:Substrate Specificity; D013917:Thrombin / Q000378:metabolism*; D014105:Tosyl Compounds
D009842:Oligopeptides; D014105:Tosyl Compounds; D013917:Thrombin
Strukturnye osnovy spetsifichnosti trombina. Rol' vtorichnykh vzaimodeĭstviĭ.