School of Chemistry, The University of Sydney, NSW 2006, Australia.
Org Biomol Chem. 2010 Aug 21;8(16):3723-33. doi: 10.1039/c003673k. Epub 2010 Jun 21.
An efficient strategy for the preparation of N-linked glycopeptides is described. The method relies on the use of side chain protecting groups on aspartic acid residues, namely the allyl and Dmab esters, which are orthogonal to those utilised in Fmoc-strategy SPPS. After peptide assembly these protecting groups were selectively removed and the resulting free side chains derivatised with a glycosylamine to afford a resin bound glycopeptide bearing a native N-linkage. Initially, N-linked glycopeptides were successfully synthesised according to this strategy, however, yields varied substantially depending on the nature of the amino acid residue situated adjacent (C-terminal) to the putative glycosylation site. This was due to generation of substantial quantities of aspartimide by-products. Aspartimide formation was overcome by incorporation of a 2,4-dimethoxybenzyl (Dmb) backbone amide protecting group on the residue adjacent to an allyl- or Dmab-protected aspartic acid residue. N-linked glycopeptides were prepared in excellent yield after the solid-phase aspartylation reactions. The utility and orthogonality of the allyl and Dmab ester solid-phase approaches were exploited in the preparation of an N-linked glycodecapeptide bearing two different carbohydrate moieties. This exemplified the efficiency of the solid-phase methodology for the preparation of glycopeptides bearing various combinations of N-linked glycans.
描述了一种用于制备 N-连接糖肽的有效策略。该方法依赖于使用天冬氨酸残基的侧链保护基，即烯丙基和 Dmab 酯，它们与 Fmoc 策略 SPPS 中使用的保护基正交。在肽组装完成后，这些保护基被选择性地去除，得到的游离侧链用糖胺衍生化，得到带有天然 N 连接的树脂结合糖肽。最初，根据该策略成功合成了 N-连接糖肽，但产率根据位于假定糖基化位点相邻（C 末端）的氨基酸残基的性质而有很大差异。这是由于生成了大量的天冬酰胺亚胺副产物。通过在烯丙基或 Dmab 保护的天冬氨酸残基相邻的残基上引入 2,4-二甲氧基苄基（Dmb）骨架酰胺保护基，克服了天冬酰胺亚胺的形成。在固相天冬酰化反应后，以优异的产率制备了 N-连接糖肽。烯丙基和 Dmab 酯固相方法的实用性和正交性在制备带有两个不同碳水化合物部分的 N-连接糖肽中得到了利用。这例示了固相方法制备带有各种 N-连接聚糖组合的糖肽的效率。
