The product of the reaction catalyed by yeast oligosaccharyltransferase was examined in order to determine the nature of the chemical linkage between the sugar and peptide. Biosynthetic donor lipid [3H] oligosaccharide was prepared and used as a substrate for yeast oligosaccharyltransferase together with a chemically synthesized peptide acceptor, N- benzoyl-Asn-Leu-Thr-NH2. The glycosylated peptide product of the in vitro reaction was ...