Abstract
Four major dextransucrase (EC 2. 4. 1. 5) preparations from Leuconostoc mesenteroides were studied in relation to their reaction products. The extracellular enzyme II, a highly aggregated form of enzyme I, synthesized the largest amount of dextran per 1 unit of enzyme. Moreover, this dextran emerged at the void volume by Sepharose 6 B chromatography. Dextran produced by the enzyme I was composed almost exclusively of water-soluble form having a molecular weight (MW) smaller than that of the product with enzyme II. Although soluble dextran produced by the intracellular enzyme (enzyme III or IV) had a low MW, ratio of insoluble dextran to total dextran was higher than that of the products with extracellular enzyme. Dextran produced by the enzyme II contained a large amount of non-α-1, 6-linkages whereas dextran produced by the enzyme I was rich in linear α-1, 6-linked structure. The structural analyses of various dextrans showed that each enzyme seemed to be responsible for the synthesis of both α-1, 6 and non-α-1, 6-linkages. Difference in the amounts and structures of dextrans suggests that the extracellular enzymes may play a major role for the dextran synthesis in vivo.
