Glycosylation (galactosylation) of (2S ,4R)-4-hydroxyproline (Hyp) in the peptide mimic N -acetyl-Hyp-N '-methylamide does not mediate the isomer equilibrium nor the rate of isomerization between the cis- and trans -prolyl amides in water. However, glycosylation of Hyp results in a downfield shift (6.5-8 ppm) of the C gamma atom of proline that is consistent with an enhanced inductive effect. Moreover, NOE experiments on the alpha-and beta-linked glycosylated AcHypNHMe amides indicate proximity between the galactose and pyrrolidine rings. This study strongly suggests that glycosylation of Hyp will have important implications on peptide backbone conformation.