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Issue 3, 2015
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Photo-induced dynamics of the heme centers in cytochrome bc1

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Abstract

The ultrafast response of cytochrome bc1 is investigated for the first time, via transient absorption spectroscopy. The distinct redox potentials of both c1- and b-hemes allow for a clear differentiation of their respective signals. We find that while the c1-heme photo-product exhibits the characteristics of a 5-coordinated species, the b-hemes presumably undergo photo-oxidation at a remarkably high quantum yield. The c1-heme iron–ligand recombination time is 5.4 ps, in agreement with previous reports on homologous cytochromes. The suggested photo-oxidized state of the b-hemes has a life-time of 6.8 ps. From this short life-time we infer that the electron acceptor must be within van der Walls contact with the heme, which points to the fact that the axial histidine residue is the electron acceptor. The different heme-responses illustrate the flexibility of the c1-heme ligation in contrast to the more rigid b-heme binding, as well as the higher electronic reactivity of the b-hemes within the bc1 complex. This study also demonstrates the remarkable connection between the heme local environment and its dynamics and, therefore, biological function.

Graphical abstract: Photo-induced dynamics of the heme centers in cytochrome bc1

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Supplementary files

Article information


Submitted
31 Oct 2014
Accepted
27 Nov 2014
First published
28 Nov 2014

Phys. Chem. Chem. Phys., 2015,17, 2143-2151
Article type
Paper
Author version available

Photo-induced dynamics of the heme centers in cytochrome bc1

A. A. P. Chauvet, A. Al Haddad, W. Kao, F. van Mourik, C. Hunte and M. Chergui, Phys. Chem. Chem. Phys., 2015, 17, 2143
DOI: 10.1039/C4CP04805A

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