Date of Award

2012

Degree Type

Thesis

Degree Name

M.Sc.

Department

Chemistry and Biochemistry

First Advisor

Michael B. Boffa

Keywords

Pure sciences, Heparin, Plasmin, Thrombin activatable fibrinolysis inhibitor

Rights

CC BY-NC-ND 4.0

Abstract

Thrombin-activatable fibrinolysis inhibitor (TAFI) is a molecular link between fibrinolysis and coagulation. TAFI gets activated either by thrombin, thrombin-thrombomodulin complex, or plasmin. Once activated, TAFIa removes carboxyl-terminal lysines from partially degraded fibrin, thus attenuating fibrinolysis. It has been previously reported that heparin accelerates plasmin-mediated activation of TAFI and increases thermal stability of TAFIa. In the present study we set out to identify heparin binding sites on TAFI. We constructed TAFI variants that contained mutations in the regions proposed to participate in the interaction with heparin. We identified several variants that showed impaired binding to heparin. Of these, K211Q/K212Q, R320A/K324A and K306A showed reduced acceleration by heparin of plasmin-mediated activation, and K327A, K327A/R330A, and R320A/K324A showed reduced stabilization of TAFIa by heparin. R320A/K324A bound very poorly to heparin, and hence might represent a useful variant with which to study the importance of glycosaminoglycans in regulating TAFI function.

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