Deperthes D, Frenette G, Brillard-Bourdet M, Bourgeois L, Gauthier F, Tremblay R R, Dubé J Y
Laboratory of Hormonal Bioregulation, CHUL Research Center, Sainte-Foy, Quebec, Canada.
J Androl. 1996 Nov-Dec;17(6):659-65.
We have recently demonstrated in liquefied human seminal plasma the presence of the novel kallikrein hK2 in association with protein C inhibitor (PCI) as a 75-kDa complex. In the present study, we showed that hK2, immediately after ejaculation, was recovered only in its free form but complex formation with PCI occurred rapidly thereafter and was completed within 10 minutes. That reaction required an enzymatically active kallikrein. In order to determine the patterns of hydrolysis of major seminal vesicle proteins, semenogelins and fibronectin were exposed to hK2 and to hK3 (prostate-specific antigen or PSA) and cleavage sequences were identified by N-terminal sequencing. Free hK2 was able to hydrolyze semenogelins and fibronectin in vitro. Most of cleavage sites were at the carboxyl-side of arginyl residues. Semenogelins were hydrolyzed to a similar extent by catalytic (and similar) concentration of either hK2 or PSA though no common cleavage sites was identified for both proteinases. Unlike semenogelins, fibronectin was hydrolyzed much more efficiently by hK2 than by PSA. These results show that hK2 is enzymatically active during a short period of time after ejaculation, that major seminal vesicle proteins can be the target of this proteolytic activity, and that hK2 and PSA have different substrate specificities.
我们最近在液化的人类精浆中证实，新型激肽释放酶hK2与蛋白C抑制剂（PCI）以75 kDa复合物的形式存在。在本研究中，我们发现射精后，hK2最初仅以游离形式存在，但此后与PCI迅速形成复合物，并在10分钟内完成。该反应需要具有酶活性的激肽释放酶。为了确定精囊主要蛋白的水解模式，将精液凝胶蛋白和纤连蛋白分别与hK2和hK3（前列腺特异性抗原或PSA）接触，并通过N端测序确定裂解序列。游离的hK2在体外能够水解精液凝胶蛋白和纤连蛋白。大多数裂解位点位于精氨酸残基的羧基侧。精液凝胶蛋白被催化浓度（且浓度相似）的hK2或PSA水解的程度相似，不过两种蛋白酶未发现共同的裂解位点。与精液凝胶蛋白不同，纤连蛋白被hK2水解的效率远高于被PSA水解的效率。这些结果表明，hK2在射精后的短时间内具有酶活性，精囊主要蛋白可能是这种蛋白水解活性的作用靶点，且hK2和PSA具有不同的底物特异性。
