Extracellular polysaccharide is a virulence factor of the most cariogenic bacteria, Streptococcus mutans. We describe a procedure for chemical analysis of this polysaccharide of S. mutans, using a well-known glucan synthesized by purified enzymes of cariogenic streptococci. Soluble and insoluble glucan from glucosyltransferase D and B respectively, were prepared and analyzed by nuclear magnetic resonance spectroscopy and methylation. Soluble alpha-glucan contained 60% of (1-->6)-linkages and 17% of branching while insoluble alpha-glucan was composed of 57% of (1-->3)- and 28% of (1-->6)-linkages with 8% branching. The described procedure could be important focusing future studies on in vivo biofilm.46551-4