VACUUM ULTRAVIOLET CIRCULAR DICHROISM OF GELLAN-FAMILY POLYMER FILMS FROM WATER AND DIMETHYL SULFOXIDE

摘要

The denaturing effect of dimethyl sulfoxide (Me(2)SO) on the conformation of the gellan-welan-rhamsan family of microbial polysaccharides is directly demonstrated by circular dichroism (CD). The three polysaccharides display strikingly similar CD spectra (140-210 nm) for films cast from Me(2)SO. The disrupting effect of Me(2)SO on gellan and welan conformations has previously been reported by others on the basis of light-scattering and viscosity studies. Films cast from aqueous solutions at room temperature show more-intense CD bands, both at 182 nm, as is also observed for aqueous solutions, and in the 150-175 nm region. These features correspond to the ordered helical chains found by X-ray diffraction studies of similarly prepared films. [References: 38]