作者:Trent Conroy、Katrina A. Jolliffe、Richard J. Payne
DOI:10.1039/c003673k
日期:——
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.
描述了一种高效的制备N-连接糖肽的策略。该方法依赖于在天冬氨酸残基上使用侧链保护基团,具体为丙烯基和Dmab酯,这些保护基团与Fmoc策略固相合成中使用的保护基团是正交的。在肽组装后,这些保护基团被选择性去除,并将得到的自由侧链与糖苷胺衍生化,以获得带有天然N-连接的树脂结合糖肽。最初,N-连接糖肽根据该策略成功合成,然而,产率因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显著变化。这是由于生成了大量天冬酰亚胺副产物。通过在靠近丙烯基或Dmab保护的天冬氨酸残基的残基上引入2,4-二甲氧基苄基(Dmb)主链酰胺保护基团,可以克服天冬酰亚胺的形成。在固相天冬酰化反应后,N-连接糖肽的产量极为优秀。利用丙烯基和Dmab酯固相方法的实用性和正交性,制备了带有两种不同碳水化合物基团的N-连接糖肽。这 exemplified了固相方法在制备带有各种N-连接糖组合的糖肽方面的高效性。