RAPID INHIBITION OF THE SPERM PROTEASE ACROSIN BY PROTEIN-C INHIBITOR
RAPID INHIBITION OF THE SPERM PROTEASE ACROSIN BY PROTEIN-C INHIBITOR
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DOI：
10.1021/bi00184a012
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发表时间：
1994-05-10
期刊：
影响因子：
2.9
通讯作者：
STONE, SR
中科院分区：
文献类型：
--
作者：
HERMANS, JM;JONES, R;STONE, SR
发现肝素是蛋白酶顶体酶酰胺分解活性的变构调节剂。在饱和浓度的肝素存在下，底物 D-Ile-Pro-Arg-p-硝基苯胺的米氏常数值降低了 4.9 倍，k(cat) 值降低了 2.5 倍。数据分析得出肝素-顶体素复合物的解离常数为0.22+/-0.04μM。精浆中存在相对高浓度的蛋白 C 抑制剂 [Laurell, M.、Christensson, A.、Abrahamson, P.、Stenflo, J. 和 Lilja, H. (1992) J. Clin.投资。 89, 1094-1101]表明该丝氨酸蛋白酶抑制剂可能参与顶体蛋白活性的控制。发现顶体素能被C蛋白抑制剂快速抑制，复合物形成的关联速率常数(k(ass))为(2.41+/-0.03)×10(5)M(-1)s(-1)。k(ass)值对肝素浓度呈钟形依赖性；它在肝素浓度为0.08至3μM之间时达到最大，并在较低和较高浓度下降低。在最佳肝素浓度下，顶体蛋白-蛋白 C 抑制剂反应的 k(ass) 值比没有肝素时高 230 倍 ((5.6 +/- 0.1) x 10(7) M(-1) s(-1))。结果表明，蛋白 C 抑制剂在顶体素活性的生理控制中可能很重要，特别是在肝素样糖胺聚糖的存在会刺激顶体素-蛋白 C 抑制剂反应的情况下。
Heparin was found to be an allosteric modulator of the amidolytic activity of the protease acrosin. In the presence of saturating concentrations of heparin, there was a 4.9-fold decrease in the value of the Michaelis constant for the substrate D-Ile-Pro-Arg-p-nitroanilide and the value of k(cat) was 2.5-fold lower. Analysis of the data yielded a dissociation constant of 0.22 +/- 0.04 mu M for the heparin-acrosin complex. The presence of relatively high concentrations of protein C inhibitor in seminal plasma [Laurell, M., Christensson, A., Abrahamson, P., Stenflo, J., and Lilja, H. (1992) J. Clin. Invest. 89, 1094-1101] suggests that this serpin may be involved in the control of the activity of acrosin. Acrosin was found to be rapidly inhibited by protein C inhibitor with the association rate constant (k(ass)) for the formation of the complex being (2.41 +/- 0.03) x 10(5) M(-1) s(-1) The value of k(ass) showed a bell-shaped dependence on the concentration of heparin; it was maximal at concentrations of heparin between 0.08 and 3 mu M and decreased at lower and higher concentrations. At the optimal heparin concentration, the value of k(ass) for the acrosin-protein C inhibitor reaction was 230-fold higher ((5.6 +/- 0.1) x 10(7) M(-1) s(-1)) than in the absence of heparin. The results suggest that protein C inhibitor may be important in the physiological control of acrosin activity, particularly where the presence of heparin-like glycosaminoglycans would stimulate the acrosin-protein C inhibitor reaction.