SYNTHESIS AND CONFORMATIONAL-ANALYSIS OF N-GLYCOPEPTIDES THAT CONTAINEXTENDED SUGAR CHAINS

Maltooligosaccharides with 2-7 sugar moieties were converted into beta -1-amino-1-deoxy derivatives and were coupled to N-alpha-fluorenylmeth oxycarbonyl-L-aspartic acid alpha-tert-butyl beta-pentafluorophenyl es ter. After trifluoroacetic acid deprotection, the resulting glycosylat ed asparagines were used as building blocks for the solid-phase synthe sis of T-cell epitopic glycopeptide analogues. The coupling efficienci es of the glycoamino acid synthons and the acid and base stability of the resulting glycopeptides indicate the applicability of this solid-p hase synthetic protocol for the incorporation of sugars that are compa rable in size with that of the natural carbohydrate antennae of N-glyc oproteins. The sugars placed into N-terminal position did not affect t he strong alpha-helical structure of the peptides, but inhibited the d isulfide-bridge formation of proximal cysteine residues in a carbohydr ate length-dependent manner.