Cottin P, Vidalenc P L, Merdaci N, Ducastaing A
Biochim Biophys Acta. 1983 Mar 16;743(2):299-302. doi: 10.1016/0167-4838(83)90227-3.
Two muscle thiol proteinases causing partial degradation of myofibrillar constituents were isolated and purified from skeletal muscle. The two proteinases that differ significantly in calcium requirements were designated respectively high- and low-Ca2+-requiring proteinase. Both are inhibited, in vitro, by a specific inhibitor which is a protein also isolated from skeletal muscle. Experiments using carboxymethylated monomeric proteinases and inhibitor-conjugated Sepharose were carried out in order to understand the mechanism of control of the proteinases by the inhibitor. The results using increasing inhibitor concentrations show a non-competitive inhibition for both enzymes. The Ki value for the low-Ca2+-requiring form was 0.3 microM, while the Ki value for the high-Ca2+-requiring form was 0.9 microM. Likewise, the low-Ca2+-requiring form needs about 3-fold more inhibitor than the high-Ca2+-requiring form for the same per cent inhibition.
从骨骼肌中分离并纯化出两种可导致肌原纤维成分部分降解的肌肉硫醇蛋白酶。这两种蛋白酶在钙需求方面存在显著差异，分别被命名为高钙需求蛋白酶和低钙需求蛋白酶。在体外，这两种蛋白酶均被一种特异性抑制剂抑制，该抑制剂也是从骨骼肌中分离得到的一种蛋白质。为了了解抑制剂对蛋白酶的控制机制，进行了使用羧甲基化单体蛋白酶和抑制剂偶联琼脂糖的实验。使用递增抑制剂浓度的实验结果表明，两种酶均表现为非竞争性抑制。低钙需求形式的Ki值为0.3微摩尔，而高钙需求形式的Ki值为0.9微摩尔。同样，对于相同百分比的抑制，低钙需求形式所需的抑制剂比高钙需求形式多约3倍。
