人胃蛋白酶1、2、3和5对胰岛素氧化B链的作用。
Action of human pepsins 1,2,3 and 5 on the oxidized B-chain of insulin.
作者信息
Roberts N B, Taylor W H
出版信息
Biochem J. 1979 Apr 1;179(1):183-9. doi: 10.1042/bj1790183.
Human pepsins 1 and 2 attack the B-chain of oxidized insulin at pH 1.7 at the same bonds as does human pepsin 3. At pH 3.5, pepsins 1 and 2 attack insulin B-chain at essentially the same bonds as at pH 1.7, but more slowly. For all three enzymes, the first bond to be hydrolysed is Phe(25)-Tyr(26), followed simultaneously by Glu(13)-Ala(14), Leu(15)-Tyr(16) and Tyr(16)-Leu(17). Human pepsin 5, however, attacks Phe(24)-Phe(25) first of all, followed by Leu(15)-Tyr(16) and Tyr(16)-Leu(17). The results suggest that each pepsin has only one active site. Acid hydrolysis indicates that the sites of enzymic cleavage are not bonds with an inherent instability at low pH.
人胃蛋白酶1和2在pH 1.7时对氧化胰岛素B链的作用位点与胃蛋白酶3相同。在pH 3.5时，胃蛋白酶1和2对胰岛素B链的作用位点与pH 1.7时基本相同，但速度较慢。对于这三种酶来说，首先被水解的键是Phe(25)-Tyr(26)，随后同时水解Glu(13)-Ala(14)、Leu(15)-Tyr(16)和Tyr(16)-Leu(17)。然而，人胃蛋白酶5首先作用于Phe(24)-Phe(25)，随后作用于Leu(15)-Tyr(16)和Tyr(16)-Leu(17)。结果表明，每种胃蛋白酶只有一个活性位点。酸水解表明，酶切位点并非是在低pH下具有固有不稳定性的键。
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