Straus J W, Polakoski K L
J Biol Chem. 1982 Jul 25;257(14):7962-4.
Acrosin is an extrinsic membrane proteinase from spermatozoa which functions in the fertilization process. Liposomes were utilized as a model system to determined possible effects of membrane association on acrosin's enzymatic activity. By comparison with solubilized enzyme, liposome-bound acrosin had a substantial reduction in the apparent affinity for "progressive" inhibitors such as leupeptin, lima bean trypsin inhibitor, soy bean trypsin inhibitor, and for a proteinase inhibitor from sperm extracts. In contrast, the liposome-bound and -solubilized enzymes were essentially identical with respect to the binding of benzamidine and p-aminobenzamidine which are competitive acrosin inhibitors. These results suggest membrane association can influence some but not all of acrosin's enzymatic properties.
顶体蛋白酶是一种来自精子的外在膜蛋白酶，在受精过程中发挥作用。脂质体被用作模型系统，以确定膜结合对顶体蛋白酶酶活性的可能影响。与可溶酶相比，结合脂质体的顶体蛋白酶对诸如亮抑酶肽、利马豆胰蛋白酶抑制剂、大豆胰蛋白酶抑制剂等“渐进性”抑制剂以及精子提取物中的一种蛋白酶抑制剂的表观亲和力大幅降低。相比之下，结合脂质体的酶和可溶酶在作为竞争性顶体蛋白酶抑制剂的苯甲脒和对氨基苯甲脒的结合方面基本相同。这些结果表明，膜结合可以影响顶体蛋白酶的一些而非全部酶学性质。
