Behaviour of dehydroalanine derivatives under hydrazinolysis conditions. Possible relevance to glycoprotein hydrazinolysis

Reactions that are relevant to the cleavage, by hydrazinolysis, of O-linked oligosaccharides from glycoproteins were studied using dehydroalanine deri vatives as models of the intermediates formed from O-glycosylated serine re sidues. Conjugate addition of hydrazine followed by cyclisation to form pyr azolidinones, if occurring during glycoprotein hydrazinolysis, could reduce the yield of released oligosaccharide. However, N-acetyldehydroalanine ami de derivatives, which modelled the dehydroalanine derivatives believed to b e intermediates in the hydrazinolysis of glycoproteins containing O-linked oligosaccharides, underwent conjugate addition but no cyclisation. Copyrigh t (C) 1999 European Peptide Society and John Wiley & Sons, Ltd.