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

High-resolution magic-angle spinning (hr-MAS) NMR spectroscopy was used to record NMR spectra of a cell paste from the marine diatom Chaetoceros mülleri. 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. mülleri. 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.