title: Purification and characterization of extracellular glucosyltransferase synthesizing water-insoluble glucan from Streptococcus rattus.
abstract: An extracellular glucosyltransferase synthesizing water-insoluble glucan (GTF-I) was purified from the culture supernatant of Streptococcus rattus strain BHT (mutans serotype b) by hydroxylapatite chromatography, DEAE-Toyopearl chromatography and preparative isoelectric focusing. The Mr of GTF-I was 155,000 by SDS-PAGE and the isoelectric point was pH 4.9. The specific activity, the optimum pH and the Km value for sucrose were 10.0 i.u. (mg protein)-1, 6.5 and 2.4 mM, respectively. The enzyme synthesized a water-insoluble glucan consisting of 69.4 mol% 1,3-alpha-linked glucose, 23.6 mol% 1,6-alpha-linked glucose, 2.6 mol% 1,3,6-alpha-branched glucose and 4.4 mol% non-reducing terminal glucose, and also a small amount (3% of the total glucan) of soluble glucan with 82.4 mol% 1,6-alpha-linked glucose. The Mr and pI values of purified GTF-I were identical with those of the enzyme in the culture supernatant.
authors.affiliation: Department of Chemistry, National Defense Medical College, Saitama, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Tsumori
authors.forename: H
authors.initials: H
authors.lastname: Kumada
authors.forename: T
authors.initials: T
authors.lastname: Umemoto
authors.forename: A
authors.initials: A
authors.lastname: Shimamura
authors.forename: H
authors.initials: H
authors.lastname: Mukasa
mesh_terms: D002850:Chromatography, Gel; D005936:Glucans / Q000378:metabolism*; D005964:Glucosyltransferases / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D007525:Isoelectric Focusing; D008970:Molecular Weight; D012995:Solubility; D013295:Streptococcus mutans / Q000201:enzymology*
chemical_list: D005936:Glucans; D005964:Glucosyltransferases