title: Immunogenic properties of the glucosyltransferase from Streptococcus sanguis OMZ 9: kinetic study of inhibition by antibodies.
abstract: An anti-glucosyltransferase serum was prepared against a pure enzyme preparation from Streptococcus sanguis OMZ 9, which synthesized both soluble and insoluble dextran. Sera, crude gamma globulins, and antibody fractions obtained after gel filtration on a Bio-Gel P200 column were used to study enzyme-antibody interactions. A strong inhibition of glucosyltransferase activity was obtained only with the purified antibody fraction. Kinetics studies showed that the anti-glucosyltransferase antibodies acted as noncompetitive inhibitors with respect to the substrate (sucrose). The addition of primer dextran in the reaction mixture during preincubation produced a diminution of the inhibition, and the antibodies acted as mixed type inhibitors with respect to dextran. The simultaneous addition of dextran and antibodies can protect the enxyme against antibody inhibition.
mesh_terms: D000907:Antibodies, Bacterial; D000918:Antibody Specificity; D000937:Antigen-Antibody Reactions; D000942:Antigens, Bacterial; D003911:Dextrans / Q000378:metabolism / Q000494:pharmacology; D004791:Enzyme Inhibitors; D005964:Glucosyltransferases / Q000276:immunology* / Q000378:metabolism; D007700:Kinetics; D013298:Streptococcus sanguis / Q000201:enzymology*; D005719:gamma-Globulins / Q000494:pharmacology
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D003911:Dextrans; D004791:Enzyme Inhibitors; D005719:gamma-Globulins; D005964:Glucosyltransferases