Parallel solid-phase synthesis of mucin-like glycopeptides
Parallel solid-phase synthesis of mucin-like glycopeptides
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DOI：
10.1016/j.carres.2005.05.023
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发表时间：
2005-09-26
影响因子：
3.1
通讯作者：
Live, D
中科院分区：
文献类型：
--
作者：
Liu, M;Barany, G;Live, D
糖肽Ac-Pro-Thr（alpha-D-GalNAc）-Thr（alpha-D-GalNAc）-Thr（alpha-D-GalNAc）-Pro-Leu-Lys-NH 2（1）具有三个连续的O-糖基化Thr残基并模拟粘蛋白2的一部分，已通过固相合成制备。还合成了7个相关的部分糖基化的肽（2-8）。这套分子允许对合成方案进行系统分析。N-α-（9-芴基甲氧羰基）-O-（3，4，6-三-O-乙酰基-2-叠氮基-2-脱氧-α-D-吡喃半乳糖基）-L-苏氨酸五氟苯基酯[Fmoc-L-Thr（Ac-3-a-D-GalN（3））-OPfp]用作结构单元，当以相对低的摩尔过量（即，类似于1.5当量）使用时，其与作为溶剂的N，N-二甲基甲酰胺（DMF）有效偶联。为了将叠氮基转化为N-乙酰基官能团，用硫代乙酸直接处理优于涉及用二硫苏糖醇（DTT）还原然后N-乙酰化的两步程序。通过用甲醇中的甲醇钠（10-15 mM;类似于5当量）处理实现溶液中1-8的有效O-脱乙酰化。还使用DMF-甲醇（17：3）中的甲醇钠（6-10 mM）（对于4和11）或甲醇中的肼（70 mM）（对于8）检查了树脂上脱乙酰化技术。在DMF-甲醇中更方便的树脂上技术给出了与溶液条件相似的产率，并且有望广泛用于固相糖肽合成。HPLC图谱显示，游离糖肽比相应的O-乙酰化衍生物更早地降解，并且保留时间随糖部分的数量而系统地变化。在水中进行的H-1 NMR研究表明，随着糖基化密度的增加，糖肽的构象组织增加。(C)2005爱思唯尔有限公司保留所有权利。
The glycopeptide, Ac-Pro-Thr(alpha-D-GalNAc)-Thr(alpha-D-GalNAc)-Thr(alpha-D-GalNAc)-Pro-Leu-Lys-NH2 (1), which features three consecutive O-glycosylated Thr residues and mimics a portion of mucin 2, has been prepared by solid-phase synthesis. Seven related, partially glycosylated peptides (2-8) were synthesized as well. This suite of molecules allowed a systematic analysis of synthetic protocols. N-alpha-(9-Fluorenylmethoxycarbonyl)-O-(3,4,6-tri-O-acetyl-2-azido-2-deoxy-alpha-D-galactopyranosyl)-L-threonine pentafluorophenyl ester [Fmoc-L-Thr(Ac-3-alpha-D-GalN(3))-OPfp] was used as a building block that coupled efficiently when used in a relatively low molar excess, that is, similar to 1.5 equiv, with N,N-dimethylformamide (DMF) as the solvent. For conversion of the azido group to the N-acetyl function, direct treatment with thioacetic acid was preferred over a two-step procedure involving reduction with dithiothreitol (DTT) followed by N-acetylation. Effective O-deacetylation of 1-8 in solution was achieved by treatment with sodium methoxide (10-15 mM; similar to 5 equiv) in methanol. On-resin deacetylation techniques were also examined, using sodium methoxide (6-10 mM) in DMF-methanol (17:3) (for 4 and 11) or hydrazine (70 mM) in methanol (for 8). The more convenient on-resin technique in DMF-methanol gave yields similar to solution conditions, and promises to be widely useful for solid-phase glycopeptide synthesis. HPLC profiles showed that free glycopeptides elute earlier than the corresponding O-acetylated derivatives, and that retention times vary systematically with the number of sugar moieties. H-1 NMR studies carried out in water showed an increase in conformational organization of glycopeptides with increased density of glycosylation. (C) 2005 Elsevier Ltd. All rights reserved.