title: Electrostatic interactions of 4-carboxy-2,6-dinitrophenyllysine-modified cytochromes c with physiological and non-physiological redox partners.
abstract: An analysis of the effect of electrostatic properties of 4-carboxy-2,6-dinitrophenyllysine (CDNP-lysine) cytochromes c on their reactions with strongly and weakly binding redox partners is given. For strongly binding systems (cytochrome-c oxidase, cytochrome-c reductase, sulphite oxidase and yeast cytochrome-c peroxidase) the magnitude of the dipole moments of the CDNP cytochromes c determines their relative reactivities. For weakly binding redox agents, such as hexacyanoferrate(III), cobalt(III)tris(1,10-phenanthroline), azurin and plastocyanin, the electrostatic potential at the haem edge accounts for the greater part of the relative activities. Relative rate data were obtained from the literature. It is concluded that the dipole moment of native cytochromes c may account for an approx. 50-fold increase in the efficiency of its physiological activity towards membrane-bound enzymes. A correction on a formula to describe the contribution of a molecular dipole moment to the ionic strength dependence of a bimolecular rate constant (Koppenol, W. H. (1980) Biophys. J. 29, 493-508) leads to an equation nearly identical to that obtained by Van Leeuwen et al. (Van Leeuwen, J.W., Mofers, F.J.M. and Verrman, E.C.I. (1981) Biochim. Biophys. Acta 635, 434-439).
authors.affiliation: Department of Chemistry, Louisiana State University, Baton Rouge 70808-1804.
authors.forename: J D
authors.initials: JD
authors.lastname: Rush
authors.forename: W H
authors.initials: WH
authors.lastname: Koppenol
mesh_terms: D001400:Azurin; D055598:Chemical Phenomena; D002621:Chemistry; D003035:Cobalt; D003574:Cytochrome c Group / Q000378:metabolism*; D003578:Cytochrome-c Peroxidase / Q000378:metabolism; D004563:Electrochemistry; D003576:Electron Transport Complex IV / Q000378:metabolism; D005292:Ferricyanides; D008239:Lysine / Q000031:analogs & derivatives*; D008565:Membrane Proteins / Q000378:metabolism; D009245:NADH Dehydrogenase / Q000378:metabolism; D009942:Organometallic Compounds; D010084:Oxidation-Reduction; D050862:Oxidoreductases Acting on Sulfur Group Donors / Q000378:metabolism; D010618:Phenanthrolines; D010970:Plastocyanin; D013816:Thermodynamics
chemical_list: C023695:4-carboxy-2,6-dinitrophenyllysine; D003574:Cytochrome c Group; D005292:Ferricyanides; D008565:Membrane Proteins; D009942:Organometallic Compounds; D010618:Phenanthrolines; D001400:Azurin; C007931:hexacyanoferrate III; C035551:triphenanthrolinecobalt(III); D003035:Cobalt; D010970:Plastocyanin; D003578:Cytochrome-c Peroxidase; D009245:NADH Dehydrogenase; D050862:Oxidoreductases Acting on Sulfur Group Donors; D003576:Electron Transport Complex IV; D008239:Lysine