Effects of Glycosylation of (2S,4R)-4-Hydroxyproline on the Conformation, Kinetics, and Thermodynamics of Prolyl Amide Isomerization
文摘
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 atom of proline that is consistent with an enhanced inductive effect. Moreover, NOE experiments on the -and -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