1977 Volume 24 Issue 4 Pages 179-185
The polysaccharide extracted from red algae Meristotheca papulosa, was separated into K-and λ-fractions by postassium chloride. The K-fraction precipitated with potassium chloride could be refractionated by calcium chloride into two components, K1-and, K2-fractions. The former remained in the supernatant after calcium chloride-fractionation, while the latter precipitated gelatinously and was also sensitive to divalent cations, such as magnesium and barium. The yields of K1-, K2-, and λ-fractions were 3.3, 17.4 and 19.1%, respectively. It was suggested by electrophoresis on cellulose acetate strips in barium acetate solution that λ-fraction consisted of at least two components. These fractions were different in chemical composition, minimum concentration for gelation and some other properties. The molar ratios of galactose, 6-O-methyl-galactose, 3, 6-anhydrogalactose and ester sulfate of K1-, K2- and λ-fractions were 1:0.17:0.70:1.91, 1:0.20:0.89:2.15 and 1:0.09:0.34:1.34, respectively. The K2-fraction surpassed other two fractions in gelation and the minimum concentration for gelation was 0.65%, but the concentration for gelation of λ-fraction especially decreased after alkali-treatment in the presence of sodium borohydride. Some differences in the infrared spectra of these fractions were observed.
