Athauda S B, Matsuzaki O, Kageyama T, Takahashi K
Department of Biophysics and Biochemistry, Faculty of Science, University of Tokyo, Japan.
Biochem Biophys Res Commun. 1990 Apr 30;168(2):878-85. doi: 10.1016/0006-291x(90)92403-m.
The amino acid sequences in the NH2-terminal region and some other parts of human gastric cathepsin E were investigated. The NH2-terminal sequencing revealed that the cathepsin E preparation which had been activated at pH 4.0 contained one major and one minor isozymes in an approximate molar ratio of 3:1. The NH2-terminal sequence of the former was very similar to but partly different from that predicted from cDNA sequencing by Azuma et al., whereas the latter had an NH2-terminal sequence identical with the predicted sequence. These results provide structural evidence for the presence of at least two isozymic forms in human gastric cathepsin E. In addition, the site of carbohydrate attachment was elucidated by isolation and analysis of a glycopeptide fraction from an enzymatic digest of cathepsin E. A single carbohydrate chain was deduced to be attached to the asparagine residue at position 34 in the major isozyme and to the corresponding asparagine residue in the minor isozyme.
对人胃组织组织蛋白酶E的NH2末端区域及其他一些部位的氨基酸序列进行了研究。NH2末端测序显示，在pH 4.0条件下激活的组织蛋白酶E制剂含有一种主要同工酶和一种次要同工酶，其摩尔比约为3:1。前者的NH2末端序列与Azuma等人通过cDNA测序预测的序列非常相似但部分不同，而后者的NH2末端序列与预测序列相同。这些结果为人类胃组织蛋白酶E中至少存在两种同工酶形式提供了结构证据。此外，通过从组织蛋白酶E的酶解物中分离和分析糖肽部分，阐明了碳水化合物连接位点。推测在主要同工酶的第34位天冬酰胺残基和次要同工酶的相应天冬酰胺残基上连接有一条单糖链。
