1eup
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(New page: 200px<br /><applet load="1eup" size="450" color="white" frame="true" align="right" spinBox="true" caption="1eup, resolution 2.1Å" /> '''X-RAY CRYSTAL STRUCTU...)
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Revision as of 12:12, 20 November 2007
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X-RAY CRYSTAL STRUCTURE OF CYTOCHROME P450ERYF WITH ANDROSTENDIONE BOUND
Overview
Several mammalian cytochrome P450 (P450) isoforms demonstrate homotropic, cooperativity with a number of substrates, including steroids and, polycyclic aromatic hydrocarbons. To identify structural factors, contributing to steroid and polycyclic aromatic hydrocarbon binding to, P450 enzymes and to determine the location of the allosteric site, we, investigated interactions of the macrolide hydroxylase P450eryF from, Saccharopolyspora erythraea with androstenedione and 9-aminophenanthrene., Spectroscopic binding assays indicate that P450eryF binds androstenedione, with an affinity of 365 microM and a Hill coefficient of 1.31 +/- 0.6 and, coordinates with 9-aminophenanthrene with an affinity of 91 microM and a, Hill coefficient of 1.38 +/- 0.2. Crystals of complexes of androstenedione, and 9-aminophenanthrene with P450eryF were grown and diffracted to 2.1 A, and 2.35 A, respectively. Electron density maps indicate that for both, complexes two ligand molecules are simultaneously present in the active, site. The P450eryF/androstenedione model was refined to an r = 18.9%, and, the two androstenedione molecules have similar conformations. The proximal, androstenedione is positioned such that the alpha-face of carbon-6 is, closest to the heme iron, and the second steroid molecule is positioned, 5.5 A distal in the active site. The P450eryF/9-aminophenanthrene model, was refined to an r = 19.7% with the proximal 9-aminophenanthrene, coordinated with the heme iron through the 9-amino group and the second, ligand positioned approximately 6 A distal in the active site. These, results establish that homotropic cooperativity in ligand binding can, result from binding of two substrate molecules within the active site, pocket without major conformational changes in the protein.
About this Structure
1EUP is a Single protein structure of sequence from [1] with HEM and ASD as ligands. This structure superseeds the now removed PDB entry 1EH0. Full crystallographic information is available from OCA.
Reference
Crystal structures of ligand complexes of P450eryF exhibiting homotropic cooperativity., Cupp-Vickery J, Anderson R, Hatziris Z, Proc Natl Acad Sci U S A. 2000 Mar 28;97(7):3050-5. PMID:10716705
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