Interaction of Cytochrome C Oxidase with Steroid Hormones

Interaction of Cytochrome C Oxidase with Steroid Hormones

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Estradiol, testosterone and other steroid hormones inhibit cytochrome c oxidase (CcO) purified from bovine heart.The inhibition is strongly dependent on concentration of dodecyl-maltoside (DM) in the assay.The plots of Ki vs [DM] are linear for both estradiol and testosterone which may indicate an 1:1 stoichiometry competition between the hormones and the detergent.

Binding of estradiol, but not of testosterone, brings about spectral Little Boys Button Ups shift of the oxidized CcO consistent with an effect on heme a33+.We presume that the hormones bind to CcO at the bile acid binding site described by Ferguson-Miller and collaborators.Estradiol is shown to inhibit intraprotein electron transfer between hemes a and a3.

Notably, neither estradiol nor testosterone suppresses the peroxidase activity of CcO.Such a specific mode of action indicates that inhibition of CcO activity by MENS BASIC TEES the hormones is associated with impairing proton transfer via the K-proton channel.