title: Inhibition of rat liver rhodanese by di-, tricarboxylic, and alpha-keto acids.
abstract: Rat liver rhodanese [EC 2.8.1.1] purified by ammonium sulfate fractionation, CM-cellulose and Sephadex G-200 chromatography yielded two active fractions (I & II). Their molecular weights were estimated to be 1.75 X 10(4) (I) and 1.26 X 10(4) (II) by the gel filtration method. Kinetic studies revealed that Fraction I rat liver rhodanese catalyzes thiocyanate formation from thiosulfate and cyanide by a double displacement mechanism. Carboxylic acids such as DL-isocitric, citric malic, pyruvic, and oxaloacetic acid were competitive inhibitors with respect to thiosulfate, whereas fumaric, succinic, and alpha-ketoglutaric acids were noncompetitive inhibitors with respect ot thiosulfate. Incubation of mitochondria with sulfate and alpha-ketoglutaric acid caused a significant decrease in rhodanese activity.
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D003486:Cyanides / Q000378:metabolism; D003998:Dicarboxylic Acids / Q000494:pharmacology*; D007523:Isocitrates / Q000494:pharmacology; D007656:Ketoglutaric Acids / Q000494:pharmacology*; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008930:Mitochondria, Liver / Q000201:enzymology; D008970:Molecular Weight; D051381:Rats; D013386:Succinates / Q000494:pharmacology; D013431:Sulfates / Q000494:pharmacology; D013466:Sulfurtransferases / Q000037:antagonists & inhibitors*; D013884:Thiosulfate Sulfurtransferase / Q000037:antagonists & inhibitors* / Q000302:isolation & purification; D013885:Thiosulfates / Q000378:metabolism; D014233:Tricarboxylic Acids / Q000494:pharmacology*
chemical_list: D003486:Cyanides; D003998:Dicarboxylic Acids; D007523:Isocitrates; D007656:Ketoglutaric Acids; D013386:Succinates; D013431:Sulfates; D013885:Thiosulfates; D014233:Tricarboxylic Acids; D013466:Sulfurtransferases; D013884:Thiosulfate Sulfurtransferase