Abstract
Summary
A cytochrome bearing ETP and a soluble, non-heme fraction, isolated from B. stearothermophilus, both catalyzed the oxidation of NADH. Although the oxidative rate in the soluble fraction was aided considerably by addition of cytochrome c and to a lesser extent by a naphthoquinone isolated from the bacillus, the rate in the ETP was only slightly increased. Flavin analysis disclosed a ratio of 3 to 1 between the soluble and particulate fractions. The former was incapable of phosphorylation whereas the ETP exhibited a P/O of 1.75. Oxidation of NADH was inhibited in both systems by 2,3-dimercaptopropanol (BAL) and in the soluble system by p-chloromercuribenzoate and amytal. Phosphorylation in an ETP suspension, inactivated by BAL or light (360 mμ) was partially restored by addition of soluble fraction. The P/O in such a mixture was 0.85, a figure which apparently represented ATP formation in the remaining functional segment of the cytochrome sequence. This phosphorylation was inhibited by 2,4-dinitro-phenol but not by dicumarol.
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