On-resin native chemical ligation for cyclic peptide synthesis.
On-resin native chemical ligation for cyclic peptide synthesis.
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DOI：
10.1021/jo049839d
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发表时间：
2004-06
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影响因子：
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通讯作者：
Judit Tulla-Puche;G. Barany
中科院分区：
文献类型：
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作者：
Judit Tulla-Puche;G. Barany
一种新的半胱氨酸衍生物，N（α）-三苯甲基-S-（9 H-咕吨-9-基）-L-半胱氨酸[Trt-Cys（Xan）-OH]已被引入用于肽合成，特别是用于制备环肽的新策略。进行以下步骤以合成环状模型肽cyclo（Cys-Thr-Abu-Gly-Gly-Ala-Arg-Pro-Asp-Phe）：（i）。Fmoc-Asp-OAl经由其游离β-羧基作为对烷氧基苄基酯侧链锚定至固体载体;（ii）.通过标准Fmoc/tBu固相化学逐步延长所述肽的链;（iii）.去除N-末端Fmoc基团;（iv）. Trt-Cys（Xan）-OH的偶联;（v）. C-末端烯丙基酯的选择性Pd（0）促进的裂解;（vi）. C-末端残基的偶联，即，H-Phe-SBzl，预活化为硫酯;（vii）.在非常温和的酸性条件下选择性去除N（α）-Trt和S-Xan保护基团;（viii）.在水性环境中通过天然化学连接的树脂上环化;和（ix）.环肽从树脂上的最终酸解裂解。评价了三种载体的策略：聚[N，N-二甲基丙烯酰胺-共-聚（乙二醇）]（PEGA），交联乙氧基化丙烯酸酯树脂（CLEAR），和聚（乙二醇）-聚苯乙烯（PEG-PS）接枝树脂支持。对于PEGA和CLEAR，以76-86%的总产率获得所需的环状产物，初始纯度约为70%，而对于PEG-PS（其在水中几乎不溶胀），结果较差。固相天然化学连接/环化方法具有方便性和特异性的优点，具有进一步推广的前景。
A novel cysteine derivative, N(alpha)-trityl-S-(9H-xanthen-9-yl)-l-cysteine [Trt-Cys(Xan)-OH] has been introduced for peptide synthesis, specifically for application to a new strategy for the preparation of cyclic peptides. The following steps were carried out to synthesize the cyclic model peptide cyclo(Cys-Thr-Abu-Gly-Gly-Ala-Arg-Pro-Asp-Phe): (i). side-chain anchoring of Fmoc-Asp-OAl via its free beta-carboxyl as a p-alkoxybenzyl ester to a solid support; (ii). stepwise chain elongation of the peptide by standard Fmoc/tBu solid-phase chemistry; (iii). removal of the N-terminal Fmoc group; (iv). coupling of Trt-Cys(Xan)-OH; (v). selective Pd(0)-promoted cleavage of the C-terminal allyl ester; (vi). coupling of the C-terminal residue, i.e., H-Phe-SBzl, preactivated as a thioester; (vii). selective removal of the N(alpha)-Trt and S-Xan protecting groups under very mild acid conditions; (viii). on-resin cyclization by native chemical ligation in an aqueous milieu; and (ix). final acidolytic cleavage of the cyclic peptide from the resin. The strategy was evaluated for three supports: poly[N,N-dimethacrylamide-co-poly(ethylene glycol)] (PEGA), cross-linked ethoxylate acrylate resin (CLEAR), and poly(ethylene glycol)-polystyrene (PEG-PS) graft resin supports. For PEGA and CLEAR, the desired cyclic product was obtained in 76-86% overall yield with initial purities of approximately 70%, whereas for PEG-PS (which does not swell nearly as well in water), results were inferior. Solid-phase native chemical ligation/cyclization methodology appears to have advantages of convenience and specificity, which make it promising for further generalization.