1upd: Difference between revisions

The tetraheme cytochrome c3 is a small metalloprotein with ca. 13,000 Da, found in sulfate-reducing bacteria, which is believed to act as a partner, of hydrogenase. The three-dimensional structure of the oxidized and, reduced forms of cytochrome c3 from Desulfovibrio desulfuricans ATCC 27774, at pH 7.6 were determined using high-resolution X-ray crystallography and, were compared with the previously determined oxidized form at pH 4.0., Theoretical calculations were performed with both structures, using, continuum electrostatic calculations and Monte Carlo sampling of, protonation and redox states, in order to understand the molecular basis, of the redox-Bohr and cooperativity effects related to the coupled, transfer of electrons and protons. We were able to identify groups that, showed redox-linked conformational changes. In particular, Glu61, His76, and propionate D of heme II showed important contributions to the, redox-cooperativity, whereas His76, propionate A of heme I, and propionate, D of heme IV were the key residues for the redox-Bohr effect. Upon, reduction, an important movement of the backbone region surrounding hemes, I and II was also identified, that, together with a few redox-linked, conformational changes in side-chain residues, results in a significant, decrease in the solvent accessibility of hemes I and II.

1UPD is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Desulfovibrio_desulfuricans Desulfovibrio desulfuricans] with HEC as [http://en.wikipedia.org/wiki/ligand ligand]. Structure known Active Site: AC1. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1UPD OCA].  

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