Characteristics of the cysteinesulfinate-forming enzyme system in rat liver

• Published in: Biochimica et biophysica acta Vol. 128; no. 2; pp. 296 - 305
• Main Authors: Ewetz, Lena, Sörbo, Bo
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.11.1966
• Subjects: Animals; Catalysis; Cysteine - metabolism; Enzymes; Hydroxylamines - pharmacology; Iron - metabolism; Liver - cytology; Liver - enzymology; Microsomes - enzymology; Mitochondria - enzymology; NADP - metabolism; Rats; Sulfinic Acids - biosynthesis; Sulfur Isotopes
• ISSN: 0926-6593; 0006-3002; 1878-223X
• DOI: 10.1016/0926-6593(66)90176-7

1. 1. The oxidation of cysteine to cysteinesulfinate by rat-liver preparations in the presence of hydroxylamine has been studied. This compound is added to the assay system in order to inhibit the enzymatic destruction of the reaction product. 2. 2. The optimum assay conditions for the enzyme system are reported. 3. 3. The reaction is catalysed by a heat-labile factor found in the soluble fraction and is stimulated by TPNH, ferrous ions and mitochondria or microsomes. The stimulating activity in the particulate fractions is heat-labile. 4. 4. The enzyme system appears to be specific for l-cysteine, as very little sulfinate formation was detected when d-cysteine, l-cystine, glutathione or cysteamine was used as substrate. 5. 5. Among different rat tissues studied, only liver contained significant activity. 6. 6. The enzyme system is inhibited by heavy-metal reagents (EDTA, cyanide, o-phenanthroline) and by the sulfhydryl reagents p-hydroxymercuribenzoate and iodoacetate, but not by arsenite.