Structure of a major oligosaccharide of PASII/PMP22 glycoprotein in bovine peripheral nerve myelin

The amino acid sequence of the glycopeptide obtained from bovine PASII/PMP22 protein in the PNS myelin was determined to be Gln-Asn-Cys-Ser-Thr, where the asparagine was glycosylated. To eliminate all the contaminated P-0 glycopeptides from the PASII/PMP22 glycopeptide preparation, we used a fluorescent probe, N-[2-(2-pyridylamino)ethyl]maleimide, which reacts with the cysteine of the PASII/PMP22 glycopeptides. The labeled PASII/ PMP22 glycopeptides were isolated by HPLC and were digested further with glycopeptidase A. The resultant oligosaccharides were conjugated with e-aminopyridine (PA) as a fluorescent tag. One major PA-oligosaccharide, OPPE1, was purified by HPLC. The structure of OPPE1 was elucidated by fast atom bombardment mass spectrometry and H-1-NMR studies and comparing the derivatives of PA-OPPE1 and PA-oligosaccharides of gamma-globulin on HPLC. The structure, SO4-3GlcA beta 1-3Gal beta 1-4GlcNAc beta 1-2Man alpha 1-6(GlcNAc beta 1 -4)(GlcNAc beta 1-2Man alpha 1-3)Man alpha 1-4GlcNAc beta 1-4(Fuc alpha 1 -6)GlcNAc-PA, was identical to the pyridylaminated form of the major oligosaccharide D8 of bovine P-0 previously reported.