Disproportionation reactions catalyzed by Leuconostoc and Streptococcus glucansucrases

Glucansucrases from Leuconostoc mesenteroides NRRL B-512F and Streptococcus mutans 6715 were found to utilize a number of D-gluco-oligosaccharides as D-glucosyl donors and as acceptors. These donors included isomaltotriose and its homologs, panose, maltotriose, and dextran. In each case, D-glucosyl groups were transferred from the donor to an acceptor sugar. When the donor sugar also acted as an acceptor, disproportionation reactions occurred. Isomaltotriose, for example, gave rise to isomaltose and isomaltotetraose initially, and to a series of isomalto-oligosaccharides eventually. In addition to forming alpha-D-(1----6) linkages in the reactions, dextransucrase from S. mutans 6715 was capable of forming alpha-D-(1----3)-linked products.