CONFORMATION OF CURDLAN IN THE TRISODIUM PHOSPHATE SOLUTION

Conformational behavior of curdlan, a (1-->3)-beta-D-glucan, in its tr isodium phosphate (Na3PO4) aqueous solution which was utilized as a fo od additive was examined. In the concentration range of 0.05 to 0.4 M where curdlan could be dissolved, it was found that the viscosity of c urdlan solution was decreased a little with the increase of the alkali ne concentration, that the absorption maximum (lambda(max)) of visible absorption spectra of a congo red solution showed a red shift from 48 5-490 to 518-520 nm by the addition of curdlan, and that a circular di chroism (CD) band was observed. When 1 M NaOH solution of curdlan was added to the curdlan 0.4 M Na3PO4 solution a drastic decreasing of vis cosity, blue shift of curdlan-congo red solution, and no CD band were observed. These results suggested that curdlan took up an ordered conf ormation in the Na3PO4 solution, but, by the addition of the NaOH solu tion a conformational transition occurred to a random coil which is si milar transformation having been observed in the NaOH solution.