%0 Journal Article %A Koga, Toshihiko %A Sato, Setsuko %A Inoue, Masakazu %A Takeuchi, Kano %A Furuta, Takushi %A Hamada, Shigeyuki %T Role of Primers in Glucan Synthesis by Glucosyltransferases from Streptococcus mutans strain OMZ176 %D 1983 %J Microbiology, %V 129 %N 3 %P 751-754 %@ 1465-2080 %R https://doi.org/10.1099/00221287-129-3-751 %I Microbiology Society, %X The effects of isomaltosaccharides of various molecular weights (isomaltose to dextran T2000) on glucan synthesis by a water-soluble glucan-synthesizing glucosyltransferase enzyme (GTase-S) and a water-insoluble glucan-synthesizing enzyme (GTase-I), both from Streptococcus mutans OMZ176, were examined. The activity of GTase-S was not affected by the addition of the isomaltosaccharides, but GTase-I was stimulated increasingly by isomaltosaccharides with degrees of polymerization more than 10. The GTase-I activity first increased and thereafter decreased slightly with increasing amounts of a soluble dextran. Maximal stimulation occurred at concentrations in the range 0·1 to 0·2 mg ml−1, when dextran T10 was used as a primer. The rate of glucan synthesis was highly enhanced by the combined action of GTase-S and GTase-I. The profile of the net activity of GTase-I in the presence of various amounts of GTase-S was similar to that of GTase-I in the presence of increasing amounts of an exogenous dextran. These results collectively suggest that soluble glucan produced by GTase-S from sucrose acts as an intrinsic primer for the glucan synthesis by GTase-I, indicating the contribution of autopriming in glucan synthesis by crude GTase of S. mutans. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-129-3-751