Structure and distribution of glucomannan and sulfated glucan in the cell walls of the red alga Kappaphycus alvarezii (gigartinales, rhodophyta)

Two new polysaccharides were isolated from the cell walls of the carrageena n producing red seaweed Kappaphycus alvarezii (Doty) Doty, They were charac terized by chemical analyses, enzymatic degradations, and nuclear magnetic resonance spectroscopy, One was a 4.0 M NaOH soluble beta-(1,4)-D-glucomann an that mostly precipitated upon neutralization and dialysis, It was compos ed of about 82 residues, and 70% of its glucose and mannose were released b y a commercial cellulase enzyme complex, The disaccharide beta -D-Man (1--> 4) D-Glc was recovered from the hydrolysate during the first hours of degra dation and confirmed the chemical structure of the polysaccharide, The othe r polysaccharide was extracted with 1.5 M NaOH and was identified as a sulf ated glucan of degree of polymerization of about 180 1,4-linked beta -gluco se containing 10% 1,3-linkages, The sulfate was located on C-6 of 64% of th e 4-linked glucose residues, A third alkali-soluble polysaccharide rich in galactose was also detected, The distribution of the glucomannan and galact ose containing polysaccharides was inversely related to the algal cell size , Potential functions of these alkali-soluble polymers are discussed in the context of cell wall polysaccharide assembly.