THE CYTOCHROME C OXIDASE OF THE HOUSE FLY, MUSCA DOMESTICA L

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Abstract
Insoluble and "soluble" forms of cytochrome c oxidase were prepared from house flies by methods described for mammalian tissue. A 4.5-fold purification was accomplished by preparing the enzyme in insoluble form (as compared with a crude water brei). The oxidase in "soluble" form was purified 20 fold. The absorption spectrum of the "soluble" prepn. from flies was similar to that from mammalian tissue, and indicated the presence of cytochromes a + a3 and b. In contrast with the corresponding mammalian enzymes, these components were not separable by the existing technics. The Soret peak seen at 440 m[mu] and the alpha peak at 600 m[mu] were due primarily to a3 and a, respectively. The oxidase activity of whole house flies was comparable with that of rat abdominal muscle. In both organisms this activity was inhibited by cyanide to approx. the same extent. The optimum buffer concn. for oxidase activity, as measured spectrophotometrically, was approx. 0.02 to 0.06 [image]. This is in agreement with results obtained for mammalian enzyme, as measured both manometrically and spectrophotometrically. The present study demonstrated the following components of the cytochrome system in house flies: b, c, a and a3.