Carbon Monoxide Oxidation by Cytochrome Oxidase in Muscle

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Abstract
An extract of pig heart catalyzed the oxidation of CO at approx. 1 [mu]l./mg./hr. Manometric measurements in 80% CO and 20% O2 closely paralleled the oxidation of C14-labeled CO. Cytochrome b, cytochrome c, diaphorase, myoglobin and catalase in a coupled system with xanthine oxidase were not responsible for CO oxidation. The heart muscle extract did not catalyze the oxidation of formate or formaldehyde. The CO oxidation was inhibited 75% by 10-4 hydroxylamine, but was unaffected by 10-3 [image]. phenylthiocarbamate. The ratios of cytochrome oxidase activity [to CO-oxidizing activity] of fractions of heart muscle extract fell within a restricted range. Cytochrome c and high rates of electron transfer increased the CO oxidation. Purified cytochrome oxidase, supplemented with cytochrome c and reduced with hydroquinone, had 40 times the CO-oxidizing activity of the heart muscle extract.