McDonald J K, Kadkhodayan S
Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston 29425.
Biochem Biophys Res Commun. 1988 Mar 15;151(2):827-35. doi: 10.1016/s0006-291x(88)80356-5.
Guinea pig spermatozoa were found to contain a fully-latent cysteine proteinase that could be unmasked by incubating epididymal sperm for 2 hr at pH 3.5 and 37 degrees C. The proteinase was identified as cathepsin L (EC 3.4.22.15) on the basis of its optimal hydrolysis of benzyloxycarbonyl-Phe-Arg-7-(4-methyl)coumarylamide (Z-Phe-Arg-NMec) at pH 5.5; lack of action on Z-Arg-Arg-NMec and Arg-NMec; urea-enhanced digestion of azocasein; marked sensitivity to thiol reagents, leupeptin, Z-Phe-Phe-CHN2, and L-trans-epoxy-succinylleucylamido(3-methyl)butane (Ep-475 or E-64-c); and insensitivity to pepstatin and serine proteinase inhibitors. Gossypol, a male antifertility agent, was inhibitory. The unmasking phenomenon was reversibly inhibited by HgCl2 and mersalyl acid, and prevented by leupeptin and Ep-475, but not by pepstatin.
发现豚鼠精子含有一种完全潜伏的半胱氨酸蛋白酶，通过在pH 3.5和37℃下将附睾精子孵育2小时可使其暴露。基于其在pH 5.5时对苄氧羰基 - 苯丙氨酸 - 精氨酸 - 7 -（4 - 甲基）香豆酰胺（Z - Phe - Arg - NMec）的最佳水解作用，该蛋白酶被鉴定为组织蛋白酶L（EC 3.4.22.15）；对Z - Arg - Arg - NMec和Arg - NMec无作用；尿素增强的偶氮酪蛋白消化；对硫醇试剂、亮抑酶肽、Z - Phe - Phe - CHN2和L - 反式 - 环氧琥珀酰亮氨酰胺（3 - 甲基）丁烷（Ep - 475或E - 64 - c）高度敏感；对胃蛋白酶抑制剂和丝氨酸蛋白酶抑制剂不敏感。棉酚，一种男性抗生育剂，具有抑制作用。HgCl2和汞撒利酸可可逆地抑制这种暴露现象，亮抑酶肽和Ep - 475可阻止这种现象，但胃蛋白酶抑制剂则不能。
