Kinetics of the inhibition of human factor Xa by full-length and truncated recombinant tissue factor pathway inhibitor
| Autor: | Ron Blezer, Theo Lindhout, George M. Willems, H.C. Hemker |
|---|---|
| Přispěvatelé: | Biochemie |
| Jazyk: | angličtina |
| Rok vydání: | 1994 |
| Předmět: |
Stereochemistry
Lipoproteins Kinetics Binding Competitive Biochemistry Dissociation (chemistry) Structure-Activity Relationship Tissue factor Reaction rate constant Tissue factor pathway inhibitor Humans Binding site Molecular Biology Binding Sites biology Chemistry Osmolar Concentration Cell Biology Recombinant Proteins Enzyme inhibitor Factor Xa biology.protein Kunitz domain Factor Xa Inhibitors Research Article |
| Zdroj: | Biochemical Journal, 297(1), 131-136. Portland Press Ltd. Scopus-Elsevier |
| ISSN: | 1470-8728 0264-6021 |
| Popis: | The inhibition equilibrium and kinetics of association and dissociation of the binding of three types of recombinant tissue factor pathway inhibitor (TFPI), namely full-length TFPI, C-terminal-truncated TFPI, and TFPI without the third Kunitz domain (TFPI1-161), to factor Xa have been measured. Formation and dissociation of the complexes were monitored by continuous measurement of the changes in the rate of hydrolysis of a peptidyl-p-nitroanilide substrate. Progress curves of product formation were fitted to a set of equations describing a one-step bimolecular inhibitory reaction in the presence of a competing substrate. For full-length TFPI the rate constants of association (kon) and dissociation (koff) were (5.1 +/- 0.7) x 10(6) M-1.s-1 and (2.6 +/- 0.9) x 10(-4)s-1 respectively. Thus, although the inhibition constant (50 pM) is far below the plasma concentration (2.5 nM) of TFPI, the half-time for transition to equilibrium in plasma is rather long (66s). The truncated forms of TFPI differ in that they have a 4-fold lower kon value but a similar dissociation rate constant. Therefore the inhibition constant, Ki, is 4-fold higher (0.2 nM) and the half-time to achieve equilibrium is prolonged to 250 s. The kon values of full-length and C-terminal-truncated TFPI, but not that of TFPI1-161, were found to decrease with increasing ionic strength. |
| Databáze: | OpenAIRE |
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