Properties of the Cytochrome c Oxidase Activity of Cytochrome b561 from Photoanaerobically Grown Rhodopseudomonas sphaeroides |
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Authors: | Takamiya Ken-ichiro |
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Institution: | Department of Biology, Faculty of Science, Kyushu University 33, Fukuoka 812, Japan |
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Abstract: | Cytochrome b561 from Rhodopseudomonas sphaeroides had cytochromec (c2) oxidase activity and a pH optimum at 6.0 for this activity.The activity was affected by the ionic strength of the reactionmixture. The apparent Km and maximal velocity (Vmax) valuesin the absence of addea salts were 14 µM and 120 nmoloxidized per min per mg protein for horse heart cytochrome c.Reduced horse heart cytochrome c was reoxidized in first-orderkinetics by this cytochrome b561. The specific activity was0.7 s1 per mg protein at 20°C at the concentrationof 30 µMM cytochrome c. Activity was inhibited by KCN and NaN3, but not by antimycin.The addition of a low concentration of KCN to the cytochromeb561 produced a change in the absorption spectrum, evidencethat KCN interacts with the heme moiety of cytochrome b561.Results of this and preceeding studies show that the cytochromeoxidase (cytochrome "o") described earlier (Sasaki et al. 1970)is cytochrome b561. (Received May 16, 1983; Accepted September 8, 1983) |
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