Energy transduction performed by a monomeric tetrahaem cytochrome

Louro, Ricardo O., Catarino, Teresa, LeGall, Jean, Turner, David L. and Xavier, Antonio V. (2001) Energy transduction performed by a monomeric tetrahaem cytochrome. Journal of Inorganic Biochemistry, 86 (1), 320. (doi:10.1016/S0162-0134(01)00278-1).

Abstract

In order to understand the mechanisms of biological energy transduction, it is essential to determine the microscopic thermodynamic parameters which describe the properties of each of the various centres involved in the reactions, as well as their interactions. These interactions between centres can then be interpreted in the light of structural features of the proteins. Redox titrations of cytochrome c3 from Desulfovibrio desulfuricans ATCC27774 followed by NMR and visible spectroscopy were analysed using an equilibrium thermodynamic model. This characterisation allows the identification of several pairs of centres for which there are clear conformational (non-Coulombic) contributions to their coupling energies, thus establishing the existence of localised redox- and acid-base-linked structural modifications in the protein (mechano-chemical coupling). The modulation of interactions between centres observed for this cytochrome favours a two-electron transition coupled with the acid-base transition which is important for the physiological function of this protein. These physiologically relevant coupling patterns are not easy to engineer by mutagenesis even when using structurally homologous proteins.

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