CHEMICAL CHARACTERISTICS OF INSOLUBLE GLUCANS FROM THE CELL-WALL OF THE MARINE GREEN-ALGA ULVA-LACTUCA (L) THURET

The chemical composition and structure of the glucan in the alkali-ins oluble cell-wall polysaccharides from the marine green seaweed Ulva la ctuca are reported. The alpha-cellulose is composed (in mol%) of gluco se (72.9), xylose (9.7), rhamnose (4.6), uronic acid (4.3), and sulfat e (8.5). The last three components do not appear to be part of the glu can as they were partially removed by methylmorpholine N-oxide treatme nt. Enzymatic hydrolysis with two commercial glucanases containing pre parations generated short oligosaccharides and sugars that were identi fied by chemical analyses and NMR spectroscopy as glucose, xylose, glu citol, cellobiose, and a new trisaccharide identified as beta-D-xylopy ranosyl-(1 --> 4)-beta-D-glucopyranosyl-(1 --> 4)-D-glucopyranose. The amorphous-like cellulose X-ray diffraction diagram obtained from the alkali-insoluble and enzyme resistant polymers was interpreted in the light of the presence of xylose-containing glucan in the insoluble cel l-wall polysaccharides from U. lactuca.