Correlation between the antitumor activity of schizophyllan and its triple helix.

is a water-soluble, non-ionic polysaccharide produced extracellularly by the fungus Schizophyllum commune^and has host-mediated antitumor activities.2) Its repeating unit consists of linearly linked /?-1,3-D-glucose residues with one /M,6-D-glucose side chain for every three main chain residues. Recently, Norisuye et al?A) found that schizophyllan dissolves as a rigid triple helix in pure water at 25C and as a single randomly coiled, chain in dimethyl sulfoxide. Very recently, we made that following findings5 ~7): (i) the schizophyllan triple helix in water melts to single, randomly coiled chain whenheated above 135C, but is not recoverable once denatured to single chains and cooled to room temperature; (ii) instead the single chains denatured at a higher temperature tha,n 135C form aggregates on cooling; (iii) the sizes of the aggregates are comparableto those of single randomcoils if the schizophyllan concentration is very low; (iv) but