Nakajima K, Kumagaye S, Nishio H, Kuroda H, Watanabe T X, Kobayashi Y, Tamaoki H, Kimura T, Sakakibara S
Peptide Institute Inc., Protein Research Foundation, Osaka, Japan.
J Cardiovasc Pharmacol. 1989;13 Suppl 5:S8-12; discussion S18. doi: 10.1097/00005344-198900135-00004.
Two disulfide analogues (types A and B) of endothelin-3 (ET-3; formerly, rat ET), sarafotoxin S6b, and apamin, were synthesized to determine their disulfide structures as in the case of endothelin-1 (ET-1; formerly human and porcine ET). The disulfide structures of ET-3 and sarafotoxin S6b were found to be identical with that of ET-1 (type A) but distinct from that of apamin (type B). The vasoconstricting activities of ET-3 and sarafotoxin S6b were about one-60th and one-third that of ET-1, respectively. Such different biological potencies between endothelins and sarafotoxin S6b could be largely attributed to the sequence heterogeneity at the N-terminal portion. ET-1 analogues were also synthesized to clarify the structure-activity relationships. The opening of any disulfide bond in the ET-1 molecule extremely decreased the activity, while oxidation of the Met residue did not alter it. Amidation of the terminal COOH group and extension of the Lys-Arg sequence to the N-terminus led to 16- and 540-fold decreases in activity, respectively. Removal of the C-terminal Trp residue resulted in complete loss of the activity. The other disulfide analogues (type B and C) of ET-1 showed markedly lower activity than the parent molecule (type A). These results indicated the importance of the whole molecule with the proper double cyclic structure for determining its active conformation.
合成了内皮素 -3（ET -3；原称大鼠 ET）、毒蜘蛛毒素 S6b 和蜂毒明肽的两种二硫键类似物（A 型和 B 型），以确定它们的二硫键结构，如同内皮素 -1（ET -1；原称人及猪 ET）的情况。发现 ET -3 和毒蜘蛛毒素 S6b 的二硫键结构与 ET -1（A 型）相同，但与蜂毒明肽（B 型）不同。ET -3 和毒蜘蛛毒素 S6b 的血管收缩活性分别约为 ET -1 的六十分之一和三分之一。内皮素与毒蜘蛛毒素 S6b 之间如此不同的生物学活性很大程度上可归因于 N 端部分的序列异质性。还合成了 ET -1 类似物以阐明构效关系。ET -1 分子中任何二硫键的打开都会极大地降低活性，而 Met 残基的氧化则不会改变其活性。末端 COOH 基团的酰胺化以及 Lys - Arg 序列向 N 端的延伸分别导致活性降低 16 倍和 540 倍。去除 C 端 Trp 残基导致活性完全丧失。ET -1 的其他二硫键类似物（B 型和 C 型）显示出比母体分子（A 型）明显更低的活性。这些结果表明具有适当双环结构的整个分子对于确定其活性构象的重要性。
