Yasumasu S, Iuchi I, Yamagami K
Life Science Institute, Sophia University, Tokyo.
J Biochem. 1989 Feb;105(2):204-11. doi: 10.1093/oxfordjournals.jbchem.a122640.
The hatching enzyme is an embryo-secreted enzyme(s) which digests the egg envelope, allowing the embryo to emerge at the time of hatching. The hatching enzyme of the fish, Oryzias latipes, has recently been found to consist of two kinds of proteases which may digest the inner layer of chorion (egg envelope) cooperatively [Yasumasu, S. et al. (1988) Zool. Sci. 5, 191-195]. In the present study, one of them, high choriolytic (egg envelope digesting) enzyme (HCE) was purified and some biochemical and enzymological properties were examined. The enzyme was a basic protein with a molecular weight of about 24 kDa, and exhibited choriolytic activity as well as proteolytic (caseinolytic) activity. The results of inhibitor studies and metal analyses strongly suggested that it was a zinc-protease. The purified HCE consisted of two probable isomers, HCE-1 and HCE-2. Both of them were markedly similar in amino acid composition, specific activities of choriolysis and proteolysis, and substrate specificity as determined using MCA-peptides. Moreover, they were not separable on SDS-PAGE, electrofocusing PAGE, or ultracentrifugal analysis, but were discriminated only on HPLC with a CM-300 column. Thus, the mixture of HCE-1 and HCE-2 could be regarded as almost a single enzyme, HCE. When it acted on an intact chorion, the purified HCE caused a remarkable swelling of its inner layer with concomitant release of peptides from it. Once the inner layer of chorion was swollen, the enzyme hardly digested it.
孵化酶是胚胎分泌的一种酶，可消化卵膜，使胚胎在孵化时破膜而出。最近发现，青鳉鱼的孵化酶由两种蛋白酶组成，它们可能协同消化卵壳的内层[安寿，S.等人（1988年）《动物学杂志》5，191 - 195]。在本研究中，其中一种高溶卵壳（消化卵膜）酶（HCE）被纯化，并对其一些生化和酶学性质进行了研究。该酶是一种碱性蛋白，分子量约为24 kDa，具有溶卵壳活性以及蛋白水解（酪蛋白水解）活性。抑制剂研究和金属分析结果强烈表明它是一种锌蛋白酶。纯化的HCE由两种可能的异构体HCE - 1和HCE - 2组成。它们在氨基酸组成、溶卵壳和蛋白水解的比活性以及使用MCA - 肽测定的底物特异性方面都明显相似。此外，它们在SDS - PAGE、等电聚焦PAGE或超速离心分析中无法分离，仅在使用CM - 300柱的HPLC上可区分。因此，HCE - 1和HCE - 2的混合物几乎可被视为单一酶HCE。当它作用于完整的卵壳时，纯化的HCE会使其内层显著肿胀，并伴随肽的释放。一旦卵壳内层肿胀，该酶就几乎不再消化它。
