W. Nieuwenhuizen, SITES IN FIBRIN INVOLVED IN THE ACCELERATION OF PLASMINOGEN ACTIVATION BY T-PA - POSSIBLE ROLE OF FIBRIN POLYMERIZATION, Thrombosis research, 75(3), 1994, pp. 343-347
Polymeric fibrin is a strong enhancer of the activation of plasminogen
by t-PA. At least two types of sites are involved in this enhancement
i.e. a site within A alpha-(148-160), and a site within gamma-(311-37
9). These sites are not accessible in fibrinogen, but are exposed upon
conversion of fibrinogen to fibrin. This explains why fibrinogen has
no rate-enhancing properties, and helps to explain the effects of fibr
in. Fibrin with its ordered structure appears to exert its rate-enhanc
ing effect by presenting the above sites for interaction with t-PA and
plasminogen; thus concentrating and correctly orienting these two rea
ctants on its surface and inducing conformational changes which lead t
o higher catalytic efficiencies.