PARENT SESSION
Posters P8A Cytochrome b-c complexes. Abstracts (382-393)

EPR caracterization of the additional heme ci of cytochrome b₆f complex. Frauke Baymann^*,1, Daniel Picot², David Stroebel², Wolfgang NItschke¹, ¹ CNRS/BIP09, Marseille cedex20, France² IBPS, Paris, France

ABSTRACT- The recently determined 3D structure of the cytochrome b6f complex (1,2) revealed the presence of an additional heme in comparison to the mitochondrial enzyme. The heme is linked to the protein by a single thioether bond and has no axial protein ligand. It is part of the Qi binding site. We present an EPR characterization of the spectral and redox properties of this heme in membranes and purified cytochrome b6f complex from the green algae Chlamydomonas reinhartdii and on membranes from Heliobacillus mobilis. The influence of inhibitor binding on the EPR signal was also adressed.

1. Stroebel, D., Choquet, Y., Popot, J.-L., Picot, D., (2003) Nature 426, 413-418
2. Kurisu, G., Zhang, H., Smith, J.L ., Cramer, W.A. (2003) Science 302, 1009-1014

KEY WORDS: heme ci, cytochrome b6f complex, EPR, quinone binding site