Cytochrome c interaction with membranes. II. Comparative study of the interaction of c cytochromes with the mitochondrial membrane |
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Authors: | J Vanderkooi M Erecińska B Chance |
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Institution: | Johnson Research Foundation, Department of Biophysics and Physical Biochemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19174 USA |
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Abstract: | A comparative study of the interaction of various cytochromes c with phospholipid vesicles and with mitochondrial membranes was undertaken. Both mammalian and yeast types of cytochrome c bind preferentially in the oxidized form as evidenced by the midpoint redox potential (Em 7.0) becoming more negative upon binding. Cytochrome c which is reincorporated into cytochrome c-depleted mitochondria is kinetically comparable with the native cytochrome c component; rate of cytochrome b oxidation is maximally restored at ratios of c1:c:a of 1:1:1. Comparison between the electron paramagnetic spectrum of cytochrome c labeled at methionine 65 or cysteine 103 reveals that upon binding to the mitochondrial membrane, the former is immobilized and not the latter. This result suggests that cytochrome c binds to the membrane at the side at which methionine 65 is located. |
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Keywords: | To whom correspondence should be addressed |
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