RELATIONSHIP BETWEEN CONFORMATION AND BIOLOGICAL RESPONSE FOR (1-]3)-BETA-D-GLUCANS IN THE ACTIVATION OF COAGULATION FACTOR-G FROM LIMULUS AMEBOCYTE LYSATE AND HOST-MEDIATED ANTITUMOR-ACTIVITY - DEMONSTRATION OF SINGLE-HELIX CONFORMATION AS A STIMULANT

The relationship between the conformation of (1 --> 3)-beta-D-glucans in gel or hydrated form and the stimulation of two types of biological responses, namely, activation of coagulation Factor G from limulus amebocyte lysate (LAL) and host-mediated antitumor activity was examined. Both types were activated by the single-helical conformation, as revealed by high-resolution, solid-state C-13-n.m.r. spectroscopy. The potency of activation of Factor G was increased over 100-fold by treatment with a NaOH solution which leads to a complete or partial conversion from the triple to the single helix. Such a single-helix specific response was also demonstrated for the antitumor activity of curdlan, although the distinction was less pronounced for branched (1 --> 3)-beta-D-glucans. The presence of the single-helix conformation was observed in schizophyllan gel, even though the triple helix is the most stable form of branched glucans in aqueous media.