Solid-phase synthesis and conformational studies of glycosylated derivatives of helper-T-cell immunogenic peptides...

3-Mercaptopropionic acid and N alpha-Fmoc serine, both with unprotected carboxyl groups, were stereospecifically glycosylated in 62-82% yields, using saccharide 1,2-trans peracetates and Lewis acid catalysis. The resulting glycosylated building blocks were used in the synthesis of derivatives of helper-T-cell stimulating peptides, with the carbohydrate moiety located at the amino terminus, or internally in the peptide chain. 1H NMR spectroscopy in Me2SO-d6 showed that the glycopeptides assumed random conformations, which were not influenced by the glycosylation or by single substitutions of amino acids in the peptide moiety.