Characterization of a β- d-(1 → 3)-glucan from the marine diatom Chaetoceros m[formula omitted]lleri by high-resolution magic-angle spinning NMR spectroscopy on whole algal cells

Abstract

High-resolution magic-angle spinning (hr-MAS) NMR spectroscopy was used to record NMR spectra of a cell paste from the marine diatom Chaetoceros m u ̈ lleri. This gave information on a cellular storage polysaccharide identified as a β- d-(1 → 3)-linked glucan, using hr-MAS one-dimensional 1H and 13C, two-dimensional 1H, 1H-COSY and 13C, 1H-correlation spectroscopy. The same structural information was deduced from the liquid state NMR data on the glucan extracted from C. m u ̈ lleri. The extracted glucan proved to be a β- d-(1 → 3)-linked glucan with a degree of polymerization of 19 and a degree of β- d-(1 → 6) branching of 0.005. The hr-MAS spectrum of the diatom showed several nonglucan resonances in the carbohydrate region of the NMR spectrum (60–103 ppm) that were shown to be noncarbohydrate resonances by means of two-dimensional 13C, 1H- and 1H, 1H-correlated NMR data.