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尿激酶原催化纤溶酶原的激活包括3个反应:(1)尿激酶原内在酶活性催化纤溶酶原转化为纤溶酶;(2)纤溶酶激活尿激酶原变成尿激酶;(3)尿激酶激活纤溶酶原,所以一直以来人们对尿激酶原激活纤溶酶原的过程知之甚少.研究发现EACA可以抑制尿激酶原催化的纤溶酶原激活.通过EACA对上述3个反应的影响进行逐个分析,观察到在EACA浓度为2 .0 mmol/L时,尿激酶原内在酶活性催化纤溶酶原激活的反应速度提高了4 .5倍,尿激酶激活纤溶酶原的反应速度提高了6倍.相反地,纤溶酶激活尿激酶原变成尿激酶的反应被抑制了50 %,此反应决定了EACA对尿激酶原催化纤溶酶原激活反应的抑制作用.该结果提示尿激酶原催化纤溶酶原激活反应的限速步骤是纤溶酶激活尿激酶原变成尿激酶,缘于纤溶酶和尿激酶原的赖氨酸结合位点的相互作用.
Priogeny of urokinase The activation of plasminogen consists of three reactions: (1) intrinsic urokinase activity catalyzes the conversion of plasminogen to plasmin; (2) plasminogen activates urokinase to become urokinase; (3) Urokinase activates plasminogen, so little has been known about the pro-urokinase-activated plasminogen process. It has been found that EACA can inhibit urokinase-induced plasminogen activation. Three reactions were analyzed one by one, observed at EACA concentration of 2.0 mmol / L, urokinase intrinsic enzyme activity catalyzed plasminogen activation reaction rate increased by 4.5 times, urokinase-activated fibrinolysis The reaction rate of zymogen was increased by a factor of 6. Conversely, the response of fibrinolytic activation of urokinase to urokinase was inhibited by 50%, which determined the inhibition of urokinase-induced plasminogen activation by EACA This result suggests that the rate-limiting step of primed plasminogen activation by urokinase is the activation of urokinase by plasmin to urokinase due to the interaction of the lysine binding site of plasmin and prourokinase effect.