Structural characterization and conformational properties of a polysaccharide isolated from Dendrobium nobile Lindl.

摘要

A water-soluble polysaccharide (JCP-40) from Dendrobium nobile Lindl. was extracted and purified. It was demonstrated as a single symmetrical peak based on HPSEC analysis and had an average molecular weight of 67.5 kDa. Combined with monosaccharide composition analysis, methylation analysis, 1D/2D NMR spectroscopy, the structural features of JCP-40 was proposed as follows: the major sugar residues of JCP-40 consisted of -> 4)-beta-D-Manp (1 -> and -> 4)-beta-D-Glcp (1 ->. Acetyl groups were found attached to the O-2 or O-3 positions on mannosyl residues based on NMR spectrum results. Rotational isomeric state (RIS)-Metropolis Monte Carlo method indicated that repeating unit increased from 30 to 120, the influence of Mw in this range affected chain flexibility. The conformational parameters (derived from R-g vs Mw and [eta] vs Mw) from HPSEC suggested a random coil conformation for JCP-40.