1fxi
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(New page: 200px<br /><applet load="1fxi" size="450" color="white" frame="true" align="right" spinBox="true" caption="1fxi, resolution 2.2Å" /> '''STRUCTURE OF THE [2FE...)
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Revision as of 13:19, 20 November 2007
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STRUCTURE OF THE [2FE-2S] FERREDOXIN I FROM THE BLUE-GREEN ALGA APHANOTHECE SACRUM AT 2.2 ANGSTROMS RESOLUTION
Overview
Crystals of a [2Fe-2S] ferredoxin (Fd) I with a relative molecular mass of, 10,480 were obtained from the blue-green alga Aphanothece sacrum. Each, asymmetric unit of the crystal contains four molecules. An electron, density map calculated by the single isomorphous replacement method with, the anomalous dispersion at 2.5 A resolution was refined by averaging the, four molecules in the asymmetric unit. Positional and isotropic thermal, parameters for the non-hydrogen atoms of the four molecules and 158 water, molecules were refined to an R-factor (R = sigma[Fo-Fc[/sigma Fo) of 0.23, by the restrained least-squares method. The estimated root-mean-square, (r.m.s.) error for the atomic positions is 0.3 A. The r.m.s. deviations of, equivalent C alpha atoms of the asymmetric-unit molecules superposed by, the least-squares method average 0.35 A. The Fd molecule has a structure, like the beta-barrel in the molecule of the [2Fe-2S] Fd from Spirulina, platensis. A [2Fe-2S] cluster is bonded covalently to the protein molecule, by four Fe-S, in which three of the Fe-S bonds are in a loop segment from, position 38 to 47. The hydrophobic core inside the beta-barrel is formed, by seven conservative residues: Val15, Val18, Ile24, Leu51, Ile74, Ala79, and Ile87. The molecular surface around Tyr23, Tyr80 and the active center, may interact with ferredoxin-NADP+ reductase. One of the two iron atoms of, the [2Fe-2S] cluster should be more easily reduced than the other because, of differences in the hydrogen-bonding scheme and the hydrophobicity, around the atoms.
About this Structure
1FXI is a Single protein structure of sequence from Aphanothece sacrum with FES as ligand. Full crystallographic information is available from OCA.
Reference
Structure of the [2Fe-2S] ferredoxin I from the blue-green alga Aphanothece sacrum at 2.2 A resolution., Tsukihara T, Fukuyama K, Mizushima M, Harioka T, Kusunoki M, Katsube Y, Hase T, Matsubara H, J Mol Biol. 1990 Nov 20;216(2):399-410. PMID:2123937
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