30 細菌由来N-結合型糖タンパク質糖鎖の立体選択的合成(口頭発表の部)

概要

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It has been revealed that certain prokaryotes, such as Campylobacter jejuni, have asparagine (Asn)-linked glycoproteins [1]. However, the structures of their glycans are distinct from those of eukaryotic origin. They consist of a bacillosamine (Bac) residue linked to Asn, α-1,4-GalNAc repeat, and branching β-Glc residue, namely GalNAc-α(1,4)-GalNAc-α(1,4)-[Glc-β(1,3)-]GalNAc-α(1,4)-GalNAc-α(1,4)-GalNAc-α(1,3)-Bac [2]. Our achievements toward the synthesis of the novel N-linked glycan have been reported, including 1) development of PFP strategy [4] for the stereoselective synthesis of α(1,4)-GalNAc repeating motifs using 4-O-pentafluoropropionyl (PFP) protected donors [5], 2) construction of the branched hexasaccharide Glc_1GalNAc_5 (7) [5], 3) syntheses of Bac (10) and N-Asn-linked Bac (11) [6] using our efficient methodology for N-glycosyl Asn [7]. Here, we describe the completion of stereoselective synthesis of a N-glycan derived from C. jejuni, a heptasaccharide, GlcGalNAc_5Bac (1) [8]. The synthesis started from Bac acceptor (9), which was consecutively glycosylated with 4-O-PFP protected donors (4, 6) to give the target heptasaccharide GlcGalNAc_5Bac (1). For the substrate of C. jejuni oligosaccharyl transferase, we also completed the synthesis of undecaprenol (39) starting from trans,trans-farnesol and nerol.
2007-08-24