Abstract
The location of (1→3)-D-glucosidic linkages in a dextran elaborated by Leuconostoc sp. IFO 12370 has been investigated by the Smith degradation technique. The polyaldehyde produced by periodate oxidation of the dextran was reduced with borohydride to the corresponding polyalcohol. Complete acid hydrolysis of the dextran polyalcohol yielded glycerol and glucose, in the molar ratio of 17:1. The polyalcohol gave upon mild acid hydrolysis glycerol and a small proportion of α-1-O-D-glucosylglycerol, which arose from the sequence →6G1→3G1→6G1→ in the parent dextran. Methylation of the polyalcohol followed by acid hydrolysis gave 1-O-methyl-glycerol (17 parts) and 2, 4-di-O-methyl-D-glu-cose (1 part), together with a trace of 2, 4, 6-tri-O-methyl-D-glucose. These results indicate that most of (1→3)-linkages in the dextran molecule are located as the branch points of the (1→6)-linked chain. The lengths of repeating unit in the various fractions of acid-degraded dextran, estimated from the ratio of glycerol and glucose derived from the poly-alcohols, were not significantly different from that of the native dextran, suggesting that random cleavage of the chain occurs during partial acid-hydrolysis.
