Regulation of fibrinolytic activity of neutrophil leukocyte elastase, plasmin, and miniplasmin by plasma protease inhibitors

Krasimir Kolev, István Léránt, Kiril Tenekejiev, Raymund Machovich

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The effect of solid-phase fibrin on the inactivation of plasmin, miniplasmin, and neutrophil leukocyte elastase (PMN-elastase) by plasma protease inhibitors (α2-antiplasmin, α1-protease inhibitor, α2- macroglobulin) was studied. In Hanks' balanced salt solution, fibrin reduces the second-order rate constant for the inhibition of PMN-elastase by α1- protease inhibitor from 8,760 x 104 to 4 x 104 M-1 · S-1 and by α2- macroglobulin from 121 x 104 to 1.8 x 104 M-1 · S-1. The rate constant for miniplasmin inactivation by α2-antiplasmin decreases from 99 x 104 to 1 x 104 M-1 · S-1, by α2-macroglobulin from 78 x 104 to 1.8 x 104 M-1 · S-1, and by α1-protease inhibitor from 0.11 x 104 M-1 · S- 1 to 0. Plasmin bound to fibrin is completely protected against α2- macroglobulin and α1-protease inhibitor, whereas the rate constant for the inactivation by its primary plasma inhibitor α2-antiplasmin is reduced from 430 x 104 to 1.08 x 104 M-1 · S-1. The competition of substrate and inhibitor for the enzyme was also studied, using fibrin preincubated with inhibitor. Under our pseudo-first-order experimental conditions, fibrin completely eliminates those interactions, the second-order rate constant of which is 1.1 x 105 M-1 · S-1 or less in a system without fibrin surface.

Original languageEnglish
Pages (from-to)17030-17034
Number of pages5
JournalJournal of Biological Chemistry
Issue number25
Publication statusPublished - Jun 24 1994


ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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