Modulation of the proteolytic activity of matrix metalloproteinase-2 (gelatinase A) on fibrinogen
Résumé
The proteolytic processing of bovine fibrinogen by Gelatinase A (MMP-2), which brings about the formation of a product unable to form fibrin clots, has been studied at 37°C. Catalytic parameters, although showing a somewhat lower catalytic efficiency with respect to thrombin and plasmin, indeed display values perfectly compatible with a meaningful pathophysiological significance of this process. A parallel molecular modelling study predicts a preferential binding of MMP-2 to the {beta}-chain of fibrinogen through its hemopexin-like domain, which has been directly demonstrated by the inhibitory effect in the presence of the exogenous hemopexin-like domain. However, the removal of this domain does not impair the interaction between MMP-2 and fibrinogen, but it certainly alters dramatically the proteolytic mechanism, producing different fragmentation intermediates. The investigation at various pH values between 6.0 and 9.3 displays a proton-linked behaviour, which is relevant for interpreting the influence on the process by environmental conditions occurring in the site of an injury. Furthermore, the action of MMP-2 on peroxynitrite-oxidized fibrinogen has been investigated, a situation possibly occurring under oxidative stress. The chemical alteration of fibrinogen, which has been shown to abolish its clotting activity, brings about only limited modifications of the catalytic parameters without altering the main enzymatic mechanism.
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