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Abstract

The development of the tetra-O-acetyl-D-glucopyranosyloxycarbonyl (AGlOC) and tetra-O-acetyl-beta -D-galactopyranosyloxycarbonyl (AGalOC) protecting groups, which are fully enzymelabile, carbohydrate-derived urethanes, is described. The protected amino acids were easily synthesized and subsequently converted into a series of model dipeptides through classical peptide couplings. Cleavage of an alpha/beta -anomeric mixture of a model AGlOC dipeptide was achieved with a "one-pot" procedure in good yield. To gain a better understanding of the enzymatic deprotection reaction, the AGalOC group was removed through a two step biotransformation (lipase catalyzed deacetylation, followed by beta -galactosidase catalyzed glycosidic bond fragmentation). Under these very mild reaction conditions tag. buffer pH 7.0, 37 degreesC), the desired N-terminal, unprotected dipeptide conjugates were obtained. The methodology was further utilized for the synthesis of an advanced tetrapeptide model system.