Araki K, Kuroki J, Ito O, Kuwada M, Tachibana S
Tsukuba Research Laboratories, Eisai Co., Ltd., Japan.
Biochem Biophys Res Commun. 1989 Oct 16;164(1):496-502. doi: 10.1016/0006-291x(89)91747-6.
Three unique inhibitors (SPAI-1, -+2, and -3) were first purified from porcine duodenal extract based on the Na+, K+-ATPase inhibitory activity. These peptide inhibitors had four disulfide bridges in common. The sequencing results of their S-carboxymethyl derivatives, lysilendopeptidase fragments, and chymotryptic peptides disclosed their entire primary structures. Both SPAI-2 and -3 consisted of 61 amino acids, respectively, and had almost the same sequences except for two amino acid substitutions, while SPAI-1 was found to lack the N-terminal twelve amino acid sequence of SPAI-2. The kinetics study revealed that SPAIs inhibited Na+, K+-ATPase by the competitive mode against Na+ and were uncompetitive with K+.
基于钠钾ATP酶抑制活性，首先从猪十二指肠提取物中纯化出三种独特的抑制剂（SPAI - 1、 - 2和 - 3）。这些肽类抑制剂共有四个二硫键。其S - 羧甲基衍生物、赖氨酰内肽酶片段和胰凝乳蛋白酶肽段的测序结果揭示了它们完整的一级结构。SPAI - 2和 - 3分别由61个氨基酸组成，除了两个氨基酸替换外，序列几乎相同，而SPAI - 1被发现缺少SPAI - 2的N端十二个氨基酸序列。动力学研究表明，SPAI通过对Na + 的竞争模式抑制钠钾ATP酶，对K + 则为非竞争性抑制。
