1m60
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Solution Structure of Zinc-substituted cytochrome c
OverviewOverview
Zinc-substituted cytochrome c has been widely used in studies of protein-protein interactions and photo-induced electron transfer reactions between proteins. However, the coordination geometry of zinc in zinc-substituted cyt c has not yet been determined; two different opinions about the coordination have been reached. Here the solution structures of zinc-substituted cytochrome c that might be five-coordinated and six-coordinated have been refined separately by using (1)H NMR spectroscopy, and the zinc coordination geometry was determined just by NOE distance constraints. Structural analysis of the energy-minimized average solution structures of both the pentacoordinated and hexacoordinated geometries indicate that that zinc in zinc-substituted cyt c should be bound to both His18 and Met80, which means that the zinc is six-coordinated. RMSD values of the family of 25 six-coordinated structures from the average structure are 0.66+/-0.13 A and 1.09+/-0.16 A for the backbone and all heavy atoms, respectively. A statistical analysis of the structure indicates its satisfactory quality. Comparison of the solution structure of the six-coordinated energy-minimized average structure of zinc-substituted cytochrome c with the solution structure of reduced cytochrome c reveals that for the overall folding the secondary structure elements are very close. The availability of the structure provides for a better understanding of the protein-protein complex and for electron transfer processes between Zn cyt c and other metalloproteins.
About this StructureAbout this Structure
1M60 is a Single protein structure of sequence from Equus caballus. Full crystallographic information is available from OCA.
ReferenceReference
Structural analysis of zinc-substituted cytochrome c., Qian C, Yao Y, Tong Y, Wang J, Tang W, J Biol Inorg Chem. 2003 Apr;8(4):394-400. Epub 2002 Dec 14. PMID:12761660
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