Er. Arndt et Es. Stevens, VACUUM-ULTRAVIOLET CIRCULAR-DICHROISM OF GELLAN-FAMILY POLYMER-FILMS FROM WATER AND DIMETHYL-SULFOXIDE, Carbohydrate research, 280(1), 1996, pp. 15-26
The denaturing effect of dimethyl sulfoxide (Me(2)SO) on the conformat
ion of the gellan-welan-rhamsan family of microbial polysaccharides is
directly demonstrated by circular dichroism (CD). The three polysacch
arides display strikingly similar CD spectra (140-210 nm) for films ca
st 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 l
ight-scattering and viscosity studies. Films cast from aqueous solutio
ns 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.