Solution structure of reduced horse heart cytochrome c

Abstract

In the frame of a broad study on the structural differences between the two redox forms of cytochromes to be related to the electron transfer process, the NMR solution structure of horse heart cytochrome c in the reduced form has been determined. The structural data obtained in the present work are compared to those already available in the literature on the same protein and the presence of conformational differences is discussed in the light of the experimental method employed for the structure determination. Redox-state dependent changes are analyzed and in particular they are related to the role of propionate-7 of the heme. Also some hydrogen bonds are changed upon reduction of the heme iron. A substantial similarity is observed for the backbone fold, independently of the oxidation state. At variance, some meaningful differences are observed in the orientation of a few side chains. These changes are related to those found in the case of the highly homologous cytochrome c from Saccharomyces cerevisiae. The exchangeability of the NH protons has been investigated and found to be smaller than in the case of the oxidized protein. We think that this is a characteristic of reduced cytochromes and that mobility is a medium for molecular recognition in vivo.

NMR basis for interprotein electron transfer gating between cytochrome c and cytochrome c oxidase

“…Previous 3D structural analysis of the reduced and oxidized states of Cyt c also indicates the redox-dependent positional shift of the N-terminal helix (12,13) (Fig. S5).…”

Cytochrome c552Mutants: Structure and Dynamics at the Active Site Probed by Multidimensional NMR and Vibration Echo Spectroscopy

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Acrolein, A Reactive Product of Lipid Peroxidation, Induces Oxidative Modification of Cytochrome c

“…The three conserved helices form a basket around the heme group. 47,48 The four flexible regions of cytochrome c called loop-1(20-35 residues), loop-2(36-59 residues), loop-3(70-85 residues), and Ctreminal helix regions are denoted based on Singh et al.…”