PubMed Health⌕ Search

Biomedical subjects

H Tsumori

Publications and source records attributed to H Tsumori.

24 records · Page 2Linked to original sources
PubMed1983

Comparative study of Streptococcus mutans extracellular glycosyltransferases by isoelectric focusing.

Extracellular glycosyltransferases from 17 strains of Streptococcus mutans were examined by analytical isoelectric focusing. Three kinds of glucosyltransferase: highly-branched-1,6-alpha-D-glucan synthetase, 1,3-alpha-D-glucan synthetase and 1,6-alpha-D-glucan synthetase, were excreted from serotype a, d and g strains. The enzymes of serotype a strains were distinguishable from those of serotypes d and g by differences in their pI values. Serotype c, e and f strains excreted basic glucosyltransferase and acidic fructosyltransferase. Serotype b strains also excreted the glucosyl- and fructosyltransferases, but the pI values were different from those of the enzymes from the other serotypes. Thus, S. mutans strains could be divided into four groups by analytical isoelectric focusing of glycosyltransferases which corresponded well to the four genetic groups.

Glucosyltransferases↗
PubMed1982

Purification and characterization of basic glucosyltransferase from Streptococcus mutans serotype c.

Streptococcus mutans Ingbritt (serotype c) was found to secrete basic glucosyltransferase (sucrose: 1,6-alpha-D-glucan 3-alpha and 6-alpha-glucosyltransferase). The enzyme preparation obtained by ethanol fractionation, DEAE Bio-Gel A chromatography, chromatofocusing and preparative isoelectric focusing was composed of three isozymes with slightly different isoelectric points (pI 8.1-8.4). The molecular weight was estimated to be 151000 by SDS-polyacrylamide gel electrophoresis. The specific activity of the enzyme was 9.8 IU per mg of protein and the optimum pH was 6.5. The enzyme was activated 2.4-fold by commercial dextran T10, and had Km values of 7.1 micro M for the dextran and 4.3 mM for sucrose. Glucan was de novo synthesized from sucrose by the enzyme and found to be 1,6-alpha-D-glucan with 17.7% of 1,3,6-branching structure by a gas-liquid chromatography-mass spectroscopy.

Chromatography, Ion Exchange↗
PubMed1982

Purification and properties of Streptococcus mutans extracellular glucosyltransferase.

Extracellular glucosyltransferase (sucrose:1,6-alpha-D-glucan 3-alpha- and 6-alpha-glucosyltransferase) was purified about 10 000-fold from the culture supernatant of Streptococcus mutans 6715. The enzyme preparation was homogeneous on polyacrylamide gel electrophoresis, isoelectric focusing and ultracentrifugation analyses. The specific activity of the enzyme was 34.9 I.U. per mg of protein and the carbohydrate content was less than 1% (w/w). The molecular weight was determined to be 149 000 +/- 5000 by sedimentation equilibrium experiment. The acidic and basic amino acids of the enzyme comprised 29 and 8.4% of total amino acid, respectively, and the isoelectric point was pH 4.1. The enzyme had the optimum pH of 5.5 and the Km value of 2.4 mM for sucrose. The water-soluble glucan, which was de novo-synthesized from sucrose by the purified enzyme, was analyzed by a gas-liquid chromatography-mass spectroscopy and was found to be 1,6-alpha-D-glucan with highly (35%) branched structure of 1,3,6-linked glucose residue.

Amino Acids↗
PubMed1982

Synthesis of glucan on the cell surface of Streptococcus mutans: chemical and scanning electron microscopic studies.

The appearance and continuing growth of extracellular material on Streptococcus mutans HS6 cells in sucrose-containing Merthiolated buffer was observed in a scanning electron microscope and was found to be related to the glucan synthesis on the cell and to adherence of the cell to a smooth surface. Cells grown in broth completely deprived of sucrose by invertase (HS6-IV) had a characteristic, slightly rugged surface structure. On incubation of HS6-IV in the sucrose-containing buffer, a few small globular particles appeared on the surface and grew to an irregular shape (globular to fibrilar) after several hours. The increase in the total glucan content of the cells paralleled the growth of the globular material, to which ferritin-conjugated anti-dextran globulin was found to bind. On the cell surface of cells harvested from conventional broth, both small globular and irregular structures, which possibly formed from sucrose in the broth, existed originally and continued to grow during incubation, along with the material newly appearing on the surface. The accumulation of glucan on the cells resulted in their adherence to a glass surface. The inhibition of growth of the extracellular material on the cells by trypsin, dextranase or anti-glucosyltransferase corresponded to the decrease in glucan synthesis and the loss of adhering ability. These results indicated that the material growing on the cell surface was glucan synthesized by glucosyltransferases.

Adhesiveness↗
PubMed1979

Effect of salts on water-insoluble glucan formation by glucosyltransferase of Streptococcus mutans.

The formation of water-insoluble glucan by extracellular glucosyltransferase from Streptococcus mutans 6715 found to be greatly stimulated by various mono- or divalent cations. An enzyme preparation, obtained by ethanol fractionation, was able to catalyze the formation of water-insoluble glucan from sucrose in the presence of monovalent cations above 100mM or divalent cations above 20 mM at neutral pH. As the concentration of monovalent and divalent cations was reduced to below 10 mM and 1 mM, respectively, the formation of insoluble glucan decreased to a negligible amount. High concentrations of these cations were found to stimulate the formation of insoluble glucan in the following ways: (i) it increased the activity of total glucosyltransferase up to 1.6- and 2.7-fold in the absence and presence of a primer dextran, respectively, and (ii) it changed the formation of soluble glucan to insoluble. It was postulated that one of the essential factors for the formation of insoluble glucan would be to keep more than two water-soluble glucan chains close to enzyme aggregates and that such interaction could be enhanced by the presence of high cation concentrations.

Carbohydrate Metabolism↗