Purification and characterization of glucosyltransferase from Streptococcus mutans OMZ176 with chromatofocusing.

A crude glucosyltransferase (GTase) preparation of Streptococcus mutans OMZ176 was fractionated by chromatography on a chromatofocusing column. It was separated into three major fractions. Fractions 1 and 3 mainly synthesized water-soluble glucan (SG) without primer dextran T-10. Dextransucrase activity of fraction 1 was not increased by the primer, although that of fraction 3 was increased. Fraction 2 synthesized only water-insoluble glucan (IG) in the absence of a primer, but mutansucrase activity of this fraction was greatly increased dose-dependently by the addition of a primer. The SG and IG synthesized by fraction 1 were rich in alpha-1,6 glucosidic linkages. On the other hand, about 80% of glucose residues of the IG synthesized by fraction 2 were alpha-1,3 linked. Both SG and IG synthesized by fraction 3 contained highly branched structures.