Structural studies on 2-acetamido-1-N-(4-L-aspartyl)-2-deoxy-β-D-glucopyranosylamine and 2-acetamido-6-O-(α-L-fucopyranosyl)-1-N-(4-L-aspartyl)-2-deoxy-β-D-glucopyranosylamine by 360-MHz proton-magnetic-resonance spectroscopy

Abstract

The 360-MHz proton magnetic resonance spectra of 2-acetamido-1-N-(4-l-aspartyl)- 2-deoxy-beta-d-glucopyranosylamine (GlcNAc beta1-> Asn) and 2-acetamido-6-O-(alpha-l-fucopyranosyl)-1-N -(4-l-aspartyl)-2-deoxy-beta-d-glucopyranosylamine (Fuc1-> 6GlcNAc1 Asn) in deuterium oxide were completely interpreted. The chemical shifts and coupling constants were refined by simulation of the spectra. By means of an adapted Karplus equation the pyranose ring conformation of the sugars was calculated.

The change of the geminal coupling constant J6a,6b in the N-acetylglucosamine residue of Fuc alpha1-> 6GlcNAc beta1-> Asn with respect to GlcNAc beta1-> Asn is proposed to be characteristic for the (1-> 6) glycosidic linkage.