Inhibition of enzymatic activity of alpha-thrombin by low molecular weight synthetic inhibitor
Kireeva, E.G.; Strukova, S.M.; Dugina, T.N.; Sokolov, V.B.; Aksinenko, A.Iu.
Biokhimiia 57(1): 21-26
1992
ISSN/ISBN: 0320-9725 PMID: 1391202 Document Number: 396886
The effect of the organophosphoric inhibitor, SA-152, on the fibrinogen-coagulating and TAME-esterase activity of bovine .alpha.-thrombin was studied. The irreversible inhibition constants (kII=1.1.cntdot.104 M-1 .cntdot. min-1, Ki=0.7.cntdot.10-4 M, k2=0.8 min-1 towards the coagulating activity and kII=0.7.cntdot.104 M-1.cntdot.min-1, Ki=0.3.cntdot.10-4 M, k2=0.2 min-1 towards the esterase activity) were determined. The SA-152 inactivated .alpha.-thrombin was dialyzed and incubated with 0.5 M and 2.5 M NaCl and 10 mM TAME. There was no reconstitution of activity of the SA-152 modified .alpha.-thrombin after dialysis and treatment with high concentrations of NaCl and TAME. Heparin interactions with the anion-binding site of the high molecular weight recognition center in the .alpha.-thrombin molecule did not significantly influence the values of the kinetic constants for the enzyme inhibition by SA-152. This finding is consistent with the hypothesis on the irreversible binding of SA-152 in the active center of the enzyme.