Yasumasu S, Iuchi I, Yamagami K
Life Science Institute, Sophia University, Tokyo.
J Biochem. 1989 Feb;105(2):212-8. doi: 10.1093/oxfordjournals.jbchem.a122641.
One of the two component proteases of the hatching enzyme of the fish, Oryzias latipes, low choriolytic enzyme (LCE), was isolated from the hatching liquid and partly characterized. The enzyme was a basic protein with molecular weight of about 25.5 kDa. Like high choriolytic enzyme (HCE), the other component of the O. latipes hatching enzyme [Yasumasu, S. et al. (1989) J. Biochem. 105, 204-211], LCE was considered to be a zinc-protease from the results of inhibitor studies and metal analyses. However, LCE was found to be distinct from HCE not only in some biochemical characteristics such as molecular weight, amino acid composition, and isoelectric point, but also in some enzymological properties such as substrate specificity, heat stability, and mode of action toward their natural substrate, chorion (egg envelope). Although LCE was almost incapable of digesting the inner layer of intact chorion, it very efficiently digested the inner layer of chorion that had been swollen previously by the action of HCE. Taking account of the fact that HCE swells the inner layer of intact chorion by partial proteolysis but does not efficiently digest the swollen chorion any more [Yasumasu, S. et al. (1989) J. Biochem. 105, 204-211], the present results demonstrated an essential role of LCE in choriolysis, in cooperation with HCE.
从鱼类青鳉孵化酶的两种组成蛋白酶之一——低溶膜酶（LCE）中，从孵化液中分离得到并对其进行了部分特性鉴定。该酶是一种碱性蛋白，分子量约为25.5 kDa。与青鳉孵化酶的另一种组成成分高溶膜酶（HCE）[安寿正等人（1989年）《生物化学杂志》105卷，204 - 211页]一样，从抑制剂研究和金属分析结果来看，LCE被认为是一种锌蛋白酶。然而，发现LCE不仅在分子量、氨基酸组成和等电点等一些生化特性方面与HCE不同，而且在底物特异性、热稳定性以及对其天然底物卵膜（卵包膜）的作用方式等一些酶学性质方面也与HCE不同。尽管LCE几乎无法消化完整卵膜的内层，但它能非常有效地消化先前因HCE作用而膨胀的卵膜内层。鉴于HCE通过部分蛋白水解使完整卵膜的内层膨胀，但不再能有效地消化膨胀后的卵膜[安寿正等人（1989年）《生物化学杂志》105卷，204 - 211页]，目前的结果表明LCE在与HCE协同作用的溶膜过程中起着重要作用。
