Comparison of the effect of histidine-rich glycoprotein and 6-aminohexanoic acid on plasmin production and fibrinolysis in vitro

Because histidine-rich glycoprotein binds to the kringle 1-3 domain of plas minogen. it may affect fibrinolysis by reducing fibrin-dependent plasmin pr oduction, and in this way it could be mechanistically analogous to 6-aminoh exanoic acid. We tested this hypothesis by comparing the effects of histidi ne-rich glycoprotein and 6-aminohexanoic acid in an in vitro assay of fibri n-dependent plasmin production mediated by tissue plasminogen activator. Wh ereas 1 mM of 6-aminohexanoic acid increased the K-m of the reaction from s imilar to 0.22 mu M to similar to 1.7 mu M, 2 mu M of histidine-rich glycop rotein had no discernible effect. Similar results were obtained in an assay based upon fibrin clot lysis. Therefore, we could not document an effect o f histidine-rich glycoprotein on the rate of fibrin-dependent plasmin produ ction. Published by Elsevier Science Ltd.