Fractionation and characterization of a Polysaccharide from the sclerotia of Pleurotus tuber-regium by preparative size-exclusion chromatography

Abstract

A kind of regenerated cellulose gel (RCG) particles were treated by toluene to obtain particles with smaller mean pore size, then was mixed with the cellulose gel with pore size of 370 and 525 nm. A preparative size-exclusion chromatography (SEC) column (700×20 mm) packed with three gel particles was used to fractionate water-soluble polysaccharide (WEP) extracted from the sclerotia of Pleurotus tuber-regium by aqueous solution. The exclusion limit and fractionation range of the stationary phase of the preparative SEC were molecular mass 8×10 5 and 5×10 3 to 8×10 5, respectively. The calibration curve of the preparative SEC was represented as: log M=13.96–0.53 Ve. The WEP sample (weight-average molecular mass M w=2.2×10 4, polydispersity=2.4) was divided into three fractions with M w ranging from 1.4×10 4 to 3.4×10 4 by the preparative SEC column, and the fractions were characterized by gas chromatography GC, SEC combined with laser light scattering (SEC-LLS) and viscometry. The unfractionated WEP exhibited triple peaks due to different molecular mass, but each fraction exhibited single peak with the polydispersity of 1.1–1.8 in the SEC patterns. The results indicated that the preparative SEC was efficient for fractionation of polysaccharides having low molecular weight and for determination of their molecular mass.