Purification and characterization of cysteic acid and cysteine sulfinic acid decarboxylase and L-glutamate decarboxylase from bovine brain.
L-Cysteic and cysteine sulfinic acids decarboxylase (CADCase/CSADCase) and L-glutamic acid decarboxylase (GADCase), the synthetic enzymes for taurine and gamma-aminobutyric acid, respectively, have been purified to homogeneity from bovine brain. Although CADCase/CSADCase and GADCase copurified through various column procedures, these two enzymes can be clearly separated by a hydroxyapatite column. The purification procedures involve ammonium sulfate fractionation, column chromatographies on Sephadex G-200, hydroxyapatite, DEAE-cellulose, and preparative polyacrylamide gel electrophoresis. The Km values for CADCase/CSADCase are 0.22 and 0.18 mM with L-cysteic and cysteine sulfinic acids as substrates, respectively. CADCase/CSADCase cannot use L-glutamate as substrate. GADCase can use L-glutamate, L-cysteic, and cysteine sulfinic acid as substrates with Km values of 1.6, 5.4, and 5.2 mM, respectively. Antibodies against CADCase/CSADCase do not crossreact with GADCase preparations and vice versa. It is concluded that CADCase/CSADCase and GADCase are two distinct enzyme entities and they are responsible for the biosynthesis of taurine and gamma-aminobutyric acid, respectively.
D000818:Animals; D001921:Brain / Q000201:enzymology*; D002262:Carboxy-Lyases / Q000276:immunology / Q000302:isolation & purification*; D002417:Cattle; D002845:Chromatography / Q000379:methods; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D005968:Glutamate Decarboxylase / Q000276:immunology / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics
D002262:Carboxy-Lyases; C019967:cysteic acid decarboxylase; D005968:Glutamate Decarboxylase; C019972:sulfoalanine decarboxylase