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Cytochrome <i>c</i>6A: discovery, structure and properties responsible for its low haem redox potential

Worrall, Jonathan AR and Luisi, Ben F and Schlarb-Ridley, Beatrix G and Bendall, Derek S and Howe, Christopher J (2008) 'Cytochrome <i>c</i>6A: discovery, structure and properties responsible for its low haem redox potential.' Biochemical Society Transactions, 36 (6). pp. 1175-1179. ISSN 0300-5127

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Abstract

<jats:p>Cytochrome c6A is a unique dithio-cytochrome of green algae and plants. It has a very similar core structure to that of bacterial and algal cytochromes c6, but is unable to fulfil the same function of transferring electrons from cytochrome f to Photosystem I. A key feature of cytochrome c6A is that its haem midpoint potential is more than 200 mV below that of cytochrome c6 (Em≈+340 mV) despite both cytochromes having histidine and methionine residues as axial haem-iron ligands. One salient difference between the haem pockets is that a valine residue in cytochrome c6A replaces a highly conserved glutamine residue in cytochrome c6. This difference has been probed using site-directed mutagenesis, X-ray crystallography and protein film voltammetry studies. It has been found that the stereochemistry of the glutamine residue within the haem pocket has a destabilizing effect and is responsible for tuning the haem's midpoint potential by over 100 mV. This large effect may have contributed to the evolution of a new biological function for cytochrome c6A.</jats:p>

Item Type: Article
Uncontrolled Keywords: cytochrome c(6A); disulfide bond; redox potential; X-ray crystallography
Subjects: Q Science > QH Natural history > QH301 Biology
Divisions: Faculty of Science and Health
Faculty of Science and Health > Life Sciences, School of
SWORD Depositor: Elements
Depositing User: Elements
Date Deposited: 23 Sep 2011 09:51
Last Modified: 18 Aug 2022 11:13
URI: http://repository.essex.ac.uk/id/eprint/1008

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