title: The use of an oscillating-tube densitometer as a tool in enzyme kinetics. Determination of the influence of sodium ascorbate on invertase, dextransucrase and dextranase.
abstract: The use of a commercial oscillating-tube densitometer with an accuracy of 4 . 10(-7) g/cm3 for the determination of enzyme-kinetics constants is tested. This method is applied to the investigation of the influence of vitamin C (sodium ascorbate) on the glycolytic enzymes invertase, dextransucrase and dextranase. Invertase is inhibited uncompetitively, dextransucrase non-competitively. There is no significant effect of the vitamin on dextranase. The comparison of the mechanisms of the three enzymes suggests that only those reaction steps are inhibited by vitamin C in which fructose is released from the enzyme.
mesh_terms: D001205:Ascorbic Acid / Q000494:pharmacology*; D003720:Densitometry / Q000379:methods; D003910:Dextranase / Q000378:metabolism*; D003911:Dextrans / Q000378:metabolism; D005964:Glucosyltransferases / Q000378:metabolism*; D007700:Kinetics; D007934:Leuconostoc / Q000201:enzymology; D008433:Mathematics; D009991:Oscillometry / Q000379:methods; D010407:Penicillium / Q000201:enzymology; D013393:Sucrase / Q000378:metabolism*; D013395:Sucrose / Q000378:metabolism
chemical_list: D003911:Dextrans; D013395:Sucrose; D005964:Glucosyltransferases; C020025:dextransucrase; D003910:Dextranase; D013393:Sucrase; D001205:Ascorbic Acid