Chain conformation of an alkali-soluble polysaccharide from mycelium of Ganoderma tsugae

摘要

An alkali-soluble polysaccharide, GM5-1, from the mycelium of Ganoderma tsugae, was fractionated by the nonsolvent addition method. The weight-average molecular mass (M-w) and intrinsic viscosity ([eta]) of fractions were studied by laser light scattering and viscometry with dimethylsulfoxide (DMSO) containing 0.25M LiCl (0.25M LiCI/DMSO) as the solvent at 30 C. The dependences of [eta] and the radius of gyration (< S-2>)(Z)(1/2) on M-w were found to be [eta] = 9.8 x 10(-2)M(w)(0.57) (cm(3) g(-1)) and < S-2>(1/2)(Z) = 1.65 x 10(-2) M-w(0.58) (nm) in the M-w range from 8.6 x 10(5) to 2.6 x 10(6). The analysis based on current theories for a wormlike chain showed that the chain conformational parameters of GM5-1 were 4.2 nm for persistence length (q) and 833 nm(-1) for linear mass density (M-L) with an obvious excluded volume effect. The results suggested the alkali-soluble polysaccharide behaves like a semiflexible chain in 0.25M LiCl/DMSO at 30 degrees C.