Role of phospholipid in the low affinity reactions between cytochrome c and cytochrome oxidase.
The steady-state oxidation of ferrocytochrome c by cytochrome oxidase monitored spectrophotometrically showed that: (1) the kinetics were strictly biphasic with purified enzyme, while mitochondrial membrane-bound enzyme exhibited multiphasic kinetics with extended low affinity phases; (2) the TNmax for the highest affinity phase was as slow as 5-10 electron X s-1 for both preparations, while for the low affinity phases it was about 45 electron X s-1 for the purified enzyme and 150 electron X s-1 for the mitochondrial membrane-bound enzyme; (3) reconstitution of purified enzyme into acidic phospholipid vesicles partially repleted the extended low affinity phases, while reconstitution into uncharged vesicles had no effect.
D000818:Animals; D002417:Cattle; D003574:Cytochrome c Group / Q000378:metabolism*; D003576:Electron Transport Complex IV / Q000378:metabolism*; D006736:Horses; D007700:Kinetics; D010084:Oxidation-Reduction; D010743:Phospholipids / Q000378:metabolism*
D003574:Cytochrome c Group; D010743:Phospholipids; D003576:Electron Transport Complex IV