Structural studies on some branched polysaccharides

Water soluble and water insoluble polysaccharides were isolated from sucrose-broth cultures of L. masantaroides strain HRRL B-1299. The polysaccharidas war&dot; identified as C-D-glueopyrans and assigned to the dextran class of polysaccharides from a consideration of their properties. Methylation and pariodata oxidations of the polysaccharides established that they have highly branched structures. The branching occurs through 1 2,6 linked glucose units. The majority of the glucose units in each case are, however, 1-6 linked although the polysaccharides do also contain smaller percentages of 1-3 linked glucosa units in intra chain positions. From the available data a repeating unit (see page 57) is proposed for each polysaccharide. Isolation of a series of isomaltose homologues from partial acid hydrolysis indicated that the polysaccharides contain chains of C-(l-6) linked glucose units which probably form the molecular skeletons. Examination of oligosaccharides from a partial acetolysis indicated that branches of the water soluble polysaccharide are more than one glucose unit long. Enzymic degradation of the water soluble polysaccharide gave oligosaccharides whose structures indicated that some branches are at least two glucose units long and probably consist of four glucosyl units.<p