COMPOSITION OF THE CELL-WALL POLYSACCHARIDE PRODUCED BY THE UNICELLULAR RED ALGA RHODELLA-RETICULATA

The composition and heterogeneity of the cell-wall polysaccharide of the red alga Rhodella reticulata was studied by means of multi-step hydrolysis and charge fractionation. The polysaccharide was found to contain xylose, 3-O-methyl pentose, glucose, galactose, rhamnose, ribose, arabinose, 4-O-methylgalactose, mannose and glucuronic acid in the approximate proportions of 12.4:6.7:1:2.2:4:0.06:0.4:2.4:0.4:1.6, and traces of 2,4-dimethyl hexose. These results differ from those obtained from a single strong acidic hydrolysis performed in a previous study, mainly in the glucuronic acid and the two methylated sugars. Fractionation of the polysaccharides by ion-exchange chromatography yielded two main fractions eluted with 0.5 M NaCl and 6 M urea. The two fractions differed in their main sugar composition, being mainly galactose and glucose, in the low salt concentration fraction and xylose and glucuronic acid in the urea fraction.