Purification and some properties of rat liver cysteine oxidase (cysteine dioxygenase).
Cysteine oxidase (cysteine dioxygenase, EC 1.13.11.20) was purified approximately 1000-fold from rat liver. The purified enzyme (protein-B) was obtained as an inactive form, which was activated by anaerobic preincubation with L-cysteine. The active form of protein-B was inactivated during aerobic incubation to produce cysteine sulfinate. This inactivation of protein-B was protected by a distinct protein in rat liver cytoplasm, namely stabilizing protein (protein-A). The Ka and Km values for L-cysteine were 0.8-10(-3) M and 1.3-10(-3) M respectively. The enzyme was strongly inhibited by Cu+ and/or Fe2+ chelating agents but not by Cu2+ chelating agent. The optimum pH of enzyme reaction was 8.5-9.5 while that of enzyme activation was 6.8-9.5, with a broad peak.
D000818:Animals; D003300:Copper / Q000494:pharmacology; D003545:Cysteine / Q000378:metabolism; D003600:Cytosol / Q000201:enzymology; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000494:pharmacology; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D010105:Oxygenases / Q000302:isolation & purification* / Q000378:metabolism; D051381:Rats
D003300:Copper; D007501:Iron; D010105:Oxygenases; D003545:Cysteine