The potency of amide protons for assignments of NMR spectra of carbohydrate chains of glycoproteins, recorded in ¹H₂ O solutions

Abstract

Three glycoprotein N-glycans, namely. a disialylated diantennary carbohydrate chain linked to Asn. a monoslalylated, fucosylated diantennary glycopeptide with bisecting N-acetylglucosamine, and a tetrasialylated. fucosylated tetra-antennary oligosaccharide, have been investigated by twodimensional NOE and HOHAHA spectroscopy in 'H,O as solvent. The amide protons of all iv-acetylglucosamme and sialic acid residues could readily be assigned. The large chemical-shift dispersion of the amide resonances of the N-acetylglucosamine residues. allowed the unambiguous assignment of every N-acetyl methyl signal. via strong NOES. Subspectra could be obtained of all Ri-acetylglucosamine residues in HOHAHA spectra. These results have as main implication that several biologically important large glycans, will not become amenable for conformational studies by multidimensional NMR in 'H,O solution.

Magnetic resonance spectroscopy of the occipital cortex and the cerebellar vermis distinguishes individual cats affected with alpha-mannosidosis from normal cats

“…These studies also reported the presence of additional peaks at 5.2 ppm region from a mixture of oligosaccharides purified from AMD brain, which were identified as anomeric protons from the partially degraded mannose sugars by 2D-spectroscopy (13,14). Thus, the in vitro and in vivo MRS findings are consistent with the known defects in the catabolic pathway of AMD.…”

“…Although in vivo MRS is often used for detection and characterization of brain tumors (10), the use of MRS in LSDs has been limited (11,12). High resolution NMR spectroscopy of brain extracts and urine samples of cats with AMD has identified resonances from several oligosaccharides, as well as anomeric proton signals from partially degraded mannose moieties using 2D-NMR spectroscopic techniques (13,14). In addition, elevated resonances due to the N-CH 3 protons of the Glc-NAc group of oligosaccharides were also observed in those studies (13).…”

Sequence‐specific

“…This process was greatly facilitated by the well-dispersed signals from amide protons in the carbohydrate groups (Fig. 5), as described by Hard et al (1991).…”