Synthetic Studies on Endothelin and Its Related Peptides Using a New S-Derotecting Reagent

内皮素（ET-1），一种21个残基的肽，由Yanagisawa等人从主动脉内皮细胞中表征，有很强的血管收缩作用ET前体cDNA的克隆和序列分析表明，ET-21的前体基因大内皮素（big ET）由38个氨基酸组成。此外，还发现了其他类型的ET，并将其命名为ET-II和ET-III。大ET可被一种独特的内肽酶“内皮素转化酶”（ECE）进一步加工为ET-21。为了评价ET的生理意义和阐明ECE的化学性质，我们采用两种交替固相法合成了人大ET及其相关肽段（ETI、II、III）。在合成研究过程中，我们提出了一种新的脱保护试剂三氟甲磺酸银和一种新的两步强酸脱保护/裂解方法[1. 3SiBr脱保护和2. HF（或Me_3SiOSO_2CF_3）裂解]的方法进行了研究 ...更多信息 用全自动合成仪进行ET-1的合成。作为氨基酸衍生物，使用Cys（Acm）、Asp（OBzl）、Glu（OBzl）、Ser（Bzl）、Thr（Bzl）、Trp（CHO）、His（Tos）、Tyr（BrZ）、Lys（CIZ）和Arg（Mts）。在最后一步中，成功地采用上述两种新方法得到了具有生物活性的ET-1。以基本上相同的方式，制备人大内皮素（ET-38）和ET-1的C-末端延长的同系物，例如ET-22、ET-23、ET-31和ET-36。根据Sheppard等人的原理，通过基于Fmoc的固相合成手动合成ET-II和ET-III，使用S-对甲氧基苄基（MBzl）保护4个Cys残基。用多种生物活性测定系统测定了人大内皮素（big ET）、大内皮素（big ET）及其相关肽的收缩血管活性，结果表明，人大内皮素（big ET）的收缩血管活性比ET-Ⅰ低两个数量级。然而，在大鼠体内试验中，人大ET在累积给药后引起动脉压的剂量依赖性升高，其效力与ET-I基本相同。C-末端延长肽ET-22、ET-23、ET-31和ET-36的活性与人大ET相当。因此，在动物体内，big-ET和所有的C-末端延长肽可能被ECE直接加工成ET-21。少

Endothelin (ET-1), a 21-residue peptide, characterized from aortic endothelial cells by Yanagisawa, et al., has a potent vasoconstrictor effect. Studies on cloning and sequencing of prepro ET cDNA have revealed the existence of the putative pecuraor of ET-21, named big endothelin (big ET), consisting of 38 amino acid residues. In addition, other types of ET were found and named ET-II, and ET-III. Big ET could be further processed to ET-21 by a unique endopeptidase named "enodothelin converting enzyme" (ECE). In order to evaluate the physiological significance of ET and clarify the chemical nature of ECE, we have synthesized ETs (ETI,II,III,) human big ET and their related peptides by two alternative solid phase method. In the course of this synthetic studies, a new Sdeprotecting reagent, silver trifluoromethanesulphonate, and a new two step hard acid deprotection/cleavage procedure [1._3SiBr deprotection and 2. HF(or Me_3SiOSO_2CF_3) cleavage] were developed.Boc-based solid phase synth … More esis of ET-1 was carried out by using automatic synthesizer. As amino acid derivatives, Cys(Acm), Asp(OBzl), Glu(OBzl), Ser(Bzl), Thr(Bzl), Trp(CHO), His(Tos), Tyr(BrZ), Lys(CIZ), and Arg(Mts) were employed. In the final step, the above two new methods were successfully employed to give a biologically active ET-I. In essentially the same manner, human big endothelin (ET-38) and C-terminally elongated homologs of ET-I, such as ET-22, ET-23, ET-31, and ET-36 were prepared. ET-II and ET-III were synthesized manually by Fmoc-based solid phase synthesis according to the principle of Sheppard, et al., using S-p-methoxybenzyl (MBzl) protection for 4 Cys residues. ETs, big ET, and their related peptides thus synthesized were assessed to the several bioassay systems.The in vitro vasoconstrictor activity of human big ET was two orders of magnitude less than that of ET-I. However, in vivo assay in rats, human big ET caused a dose dependent rise of arterial pressure after the cumulative administration in essentially the same potency as that of ET-I. The activities of C-terminally elongated peptides, ET-22, ET-23, ET-31, and ET-36, were comparable to that human big ET. Thus, it was suggested that big-ET and all of C-terminally elongated peptides might be processed directly to ET-21 by ECE in animal body. Less