Solid-phase synthesis and characterization of N-methyl-rich peptides
Solid-phase synthesis and characterization of N-methyl-rich peptides
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DOI：
10.1111/j.1399-3011.2004.00213.x
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发表时间：
2005-02-01
期刊：
影响因子：
--
通讯作者：
Giralt, E
中科院分区：
文献类型：
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作者：
Teixidó, M;Albericio, F;Giralt, E
在固相上合成了研究血脑屏障转运相关因素的项目所需的肽库。由于肽中 N-甲基氨基酸含量高，它们的合成具有挑战性，并构成了此处介绍的工作的基础。受保护的N-甲基氨基酸与N-甲基氨基酸的偶联通常产率较低。 (7-氮杂苯并三唑-1-基氧基)三(吡咯烷)鏻六氟磷酸盐(PyAOP)或PyBOP/1-羟基-7-氮杂苯并三唑(HOAt)是这些偶联中最有前途的偶联试剂。当肽的 N 末端位置含有乙酰化的 N-甲基氨基酸时，在三氟乙酸 (TFA) 从树脂上裂解肽的过程中会发生 Ac-N-甲基氨基酸的损失。本文描述了由酸性裂解引起的其他副反应，包括连续 N-甲基氨基酸之间的断裂和二酮哌嗪 (DKP) 的形成。裂解时间对合成结果有很大影响。最后，由于构象异构体之间的转化缓慢，富含 N-甲基的肽的高效液相色谱 (HPLC) 谱显示出多个峰。
A library of peptides required for a project investigating the factors relevant for blood-brain barrier transport was synthesized on solid phase. As a result of the high N-methylamino acid content in the peptides, their syntheses were challenging and form the basis of the work presented here. The coupling of protected N-methylamino acids with N-methylamino acids generally occurs in low yield. (7-azabenzotriazol-1-yloxy)tris( pyrrolidino) phosphonium hexafluorophosphate (PyAOP) or PyBOP/1-hydroxy-7-azabenzotriazole (HOAt), are the most promising coupling reagents for these couplings. When a peptide contains an acetylated N-methylamino acid at the N-terminal position, loss of Ac-N-methylamino acid occurs during trifluoroacetic acid (TFA) cleavage of the peptide from the resin. Other side reactions resulting from acidic cleavage are described here, including fragmentation between consecutive N-methylamino acids and formation of diketopiperazines (DKPs). The time of cleavage is shown to greatly influence synthetic results. Finally, high-performance liquid chromatography (HPLC) profiles of N-methyl-rich peptides show multiple peaks because of slow conversion between conformers.