PROPERTIES OF AURICULARIA-AURICULA-JUDAE BETA-D-GLUCAN IN DILUTE-SOLUTION

A water-soluble glucan A was isolated from the fruit body of Auricular ia auricula-judae. It is composed of a backbone chain of beta-(1 --> 3 )-linked D-glucose residues, two out of three glucose residues being s ubstituted at C-6 positions with a single glucose unit. The weight ave rage molecular weight Mw, number average molecular weight Mn, and intr insic viscosity [eta] of the fractionated samples were studied at 25 d egrees C in water and in dimethylsulfoxide(DMSO). The Mark-Houwink equ ation was established as [eta] = 6.10 x 10(-4) Mw(1.14) for the glucan A having Mw ranging from 9 X 10(5) to 1.6 X 10(6) in water. The value s of [eta] in water are far higher than those in DMSO, but the values of Mn measured in water are the same as those in DMSO. Analysis of Mw and [eta] in terms of the known theories for rods and wormlike chains yielded 1030 +/- 100 nm(-1), 90 +/- 20 nm, 1.3 +/- 0.3 nm, and 0.26 +/ - 0.03 nm for molar mass per unit contour length M(L), persistence len gth q, diameter d, and contour length h per main-chain glucose residue , respectively. The present data suggest that glucan A dissolves in wa ter as single-stranded helical chains and in DMSO as semiflexible chai ns. (C) 1995 John Wiley & Sons, Inc.