| Popis: |
Investigations were made of the mechanism of fibrinolysis through evaluations of the role of enzymes and enzyme inhibitors. Specifically, studies were made utilizing the enzyme ribonuclease to inhibit the lysis of fibrin clots (bovine and human) by bovine and/or human plasmin (fibrinolysis). It was found that the optimum pH range for effective inhibition of plasmin by ribonuclease is from 8-9. Increases in temperature were found to increase plasmin activity but tend to reduce the inhibitory action of ribonuclease on plasmin activity. Data obtained indicate that lysis of a fibrin clot by plasmin occurs in two steps: (1) depolymerization of the fibrin clot and (2) subsequent hydrolysis of the depolymerizied fibrin to amino acids. Both steps are inhibited by ribonuclease via a plasmin - ribonuclease complex not involving the moiety of the ribonuclease molecule involved in ribonucleic acid degradation. Moreover, it was found that dilute acid hydrolysis of bovine pancreatic ribonuclease results in a loss of the nuclease activity of ribonuclease but not its antiplasmin activity. Studies made on the role of heparin and ribonuclease in fibrinolysis indicate that heparin inhibits the antiplasmin activity of ribonuclease. In addition, it has been observed that bovine pancreatic ribonuclease will inhibit the liquifaction of fibrin clots in vitro by heparin in low concentration (1-10 N1H units) in the absence of plasmin. No other components of the fibrin possess ribonuclease activity. (Author) |
