作者:Hiroo Yonezawa、Tetsuya Wada
DOI:10.1246/bcsj.62.3730
日期:1989.11
Photoaffinity reagents for pepsin [Ala–Gly–Phe(N3), Gly–Gly–Phe(N3)–Phe–Gly–OEt, Gly–Gly–Phe–Phe(N3)–Gly–OEt] were synthesized by a solution method. The pentapeptides were cleaved rapidly at the peptide bond between two aromatic amino acid residues by pepsin. This shows that Phe(N3) residues of the photoaffinity reagents bind with the S1 or S1′ site of pepsin. Pepsin was irradiated with photoaffinity reagents and the remaining activity was measured. The pepsin activity was decreased more rapidly in the presence of photoaffinity reagents, compared with that in the absence of photoaffinity reagents. Photoaffinity labeling occured at pH 2.0; however, did not occur at pH 4.0. Photoaffinity labeling of pepsin with 3H-labeled Gly–Gly–Phe(N3)–Phe–Gly–OEt showed that about 9% of the pepsin bound covalently with the photoaffinity reagent.
采用溶液法合成了胃蛋白酶光亲和试剂[Ala-Gly-Phe(N3)、Gly-Gly-Phe(N3)-Phe-Gly-OEt、Gly-Gly-Phe-Phe(N3)-Gly-OEt]。这些五肽在胃蛋白酶的作用下迅速裂解了两个芳香族氨基酸残基之间的肽键。这表明光亲和试剂的 Phe(N3) 残基与胃蛋白酶的 S1 或 S1′ 位点结合。用光亲和试剂照射胃蛋白酶并测量其剩余活性。与没有光亲和试剂时相比,有光亲和试剂时胃蛋白酶的活性下降得更快。光亲和标记在 pH 值为 2.0 时发生,但在 pH 值为 4.0 时没有发生。用 3H 标记的 Gly-Gly-Phe(N3)-Phe-Gly-OEt 对胃蛋白酶进行光亲和标记显示,约有 9% 的胃蛋白酶与光亲和试剂共价结合。