Role of phospholipid in the low affinity reactions between cytochrome c and cytochrome oxidase |
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Authors: | S H Speck C A Neu M S Swanson E Margoliash |
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Affiliation: | Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, IL 60201, USA |
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Abstract: | 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. |
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Keywords: | Polyphasic kinetics Acidic phospholipid Mitochondrial membrane |
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