Structure and Conformation Behavior of a Glucan from Spores of Ganoderma lucidum (Fr.) Karst.

A novel polysaccharide designated as β D glucan LB NB, 21 D -24.52 0(c=0.81, H 2O)and Mr 4.7×10 4, wa s isolated and purified from a 0.5 mol/L sodium hydroxide extract of the sporode rm broken spores of Ganoderma lucidum. The results of NMR experiments, tota l hydrolysis, methylation analysis and Smith degradation of LB NB showed that i t possesses a backbone consisting of(1→3) β D glucosyl residues, about two out of nine glucosyl residues being substituted at O 6 by single glucosyl group s. The conformational behavior of LB NB was studied. Measurements by specific r otations and viscometry showed that the glucan LB NB takes an ordered structure in water or lower concentration(0.05 mol/L)alkaline solution and dissolves as random coil in higher concentration(0.1 mol/L)alkaline solution or in dimethyl sulfoxide(Me 2SO). The ordered conformation melts into flexible chains with the increase of the concentration of alkali or the V DMSO (v/v)of H 2O Me 2SO mixture. The former dissociation is reversible and the later is irreve rsible. The complex formation with Congo red indicated that the LB NB takes ne ither triple stranded helical nor randomly coiled conformation in neutral or sl ightly alkaline solution, and most probably, it should contain single helical st ructure in aqueous solution. According to immunological test, the LB NB showed remarkable activity of stimulating the proliferation of T Cells in vitro, g iving a good example for Kulickes statement .