Triple helix of beta-D-glucan from Lentinus Edodes in 0.5 M NaCl aqueous solution characterized by light scattering

beta-(1 -->3)-D-glucan with (1 -->6) branching (L-FV-I) from Lentinus edodes in water was degraded into seven fractions of different molecular weights by ultrasonic irradiation. Weight-average molecular weight M,, radius of gyration (1/2)(5) and intrinsic viscosity [eta] of the beta -D-glucan and its fractions in 0.5 M NaCl aqueous solution and dimethylsulfoxide (DMSO) were studied by multi-angle laser light scattering (MALLS), GPC combined with MALLS, and viscometry. M, dependence of [eta] for the glucan in 0.5 M NaCl aqueous solution was represented approximately by [eta] =7.69 x 10(-6) M-w(1.32) (cm(3) g(-1)) at M-w from 1.87 X 10(5) to 1.20 X 10(6) at 25 degreesC. GPC chromatograms of the glucans in aqueous solution contained two peaks, a main peak corresponding to triple-stranded chains with molecular weight M-w,M-m, and small second peak corresponding to fragments of single chains with M-w,M-s (about 20 +/-5% content). Analysis of M-w,M-m and (1/2)(z,m) in term of the known theory for wormlike chains yielded 2180 +/- 100 nm(-1), 120 +/- 10 nm and 0.31 nm for molar mass per unit contour length M-L, persistence length q, and contour length h per main-chain glucose residue, respectively, which agree closely with theory data of triple-helical chains and reported parameters for triple-helix schizophyllan in 0.01 M NaOH aqueous solution. The ratios of M-w,M-m, in 0.5 M NaCl to M, in DMSO were calculated to be roughly 3. The predominant species of the glucan in 0.5 M NaCl aqueous solution exist as triple-helical chains with high rigidity, and in DMSO as single-flexible chains.