Two different conformations of the antitumor beta-D-glucan produced by Sclerotinia sclerotiorum IFO 9395.

The antitumor beta-D-glucan [SSG, (1----3)-linked with a D-glucosyl group attached to position 6 of alternate units] produced by Sclerotinia sclerotiorum IFO 9395 afforded a gel in neutral aqueous solution which gave no 13C-n.m.r. signals. Signals appeared on the addition to the gel of sodium hydroxide to 0.15M and the line-width was narrowest near 0.25M base (gel-to-sol transition). SSG bound to Congo Red and shifted the lambda max in a manner similar to that of curdlan. Neutralisation of the sol regenerated the gel. SSG and regenerated SSG showed different c.p.-m.a.s. 13C-n.m.r. spectra, especially the signals for C-3 which appeared at 86 and 89 p.p.m., respectively. The c.p.-m.a.s. spectrum of regenerated SSG was similar to that of curdlan, suggesting a helical structure. Thus, SSG and regenerated SSG appear to have different conformations.