Synthesis of linear-B saccharopeptides via enzymatic galactosylation of non-natural glucosamide accepters

A series of D- and L-glycopyranuronic acids are coupled to glucosamines to give saccharopeptides. These 'disaccharides'. in which the acetyl moiety of the natural N-acetyl-glucosamine is replaced by various sugar acids, turne d out to be surprisingly good substrates for beta (1-4)-galactosyl-transfer ase and alpha (1-3)-galactosyl-transferase. The enzymes transfer successive ly two galactose units from the donor UDP-galactose onto these acceptor sub strates. despite the far reaching, alterations, regio- and stereospecifical ly in the expected manner to give linear-B saccharopeptides. (C) 2001 Elsev ier Science Ltd. All rights reserved.