One- and two-dimensional NMR studies of the N-terminal portion of glycophorin A at 11.7 Tesla

One- and two-dimensional nuclear magnetic resonance (NMR) spectroscopy (at 11.7 Tesla) was used to gain some structural and spectral information about glycophorin A^M, glycophorin A^M tryptic glycopeptide, a related pentapeptide, and two related monoglycosylated pentapeptides. The protein spectral information suggests that the highly glycosylated N-terminus of glycophorin does not seem to possess a unique tertiary structure. Furthermore, the spectral information provided by the carbohydrate residues also indicates that there is no strong carbohydrate-protein interaction resulting in a unique tertiary structure. This result does not preclude any unique protein-carbohydrate interactions. For the small monoglycosylated pentapeptide containing -d-GalNAc attached to Thr, a unique NOESY cross-peak was observed between the anomeric proton and the -proton of Thr. A cross-peak between the -proton of Ser and the anomeric proton was not observed for a related monoglycosylated pentapetide containing -d-GalNAc O-linked to Ser.