1phc
From Proteopedia
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CRYSTAL STRUCTURE OF SUBSTRATE-FREE PSEUDOMONAS PUTIDA CYTOCHROME P450
Overview
The crystal structure of Pseudomonas putida cytochrome P-450cam in the, substrate-free form has been refined at 2.20-A resolution and compared to, the substrate-bound form of the enzyme. In the absence of the substrate, camphor, the P-450cam heme iron atom is hexacoordinate with the sulfur, atom of Cys-357 providing one axial heme ligand and a water molecule or, hydroxide ion providing the other axial ligand. A network of, hydrogen-bonded solvent molecules occupies the substrate pocket in, addition to the iron-linked aqua ligand. When a camphor molecule binds, the active site waters including the aqua ligand are displaced, resulting, in a pentacoordinate high-spin heme iron atom. Analysis of the Fno camphor, - F camphor difference Fourier and a quantitative comparison of the two, refined structures reveal that no detectable conformational change results, from camphor binding other than a small repositioning of a phenylalanine, side chain that contacts the camphor molecule. However, large decreases in, the mean temperature factors of three separate segments of the protein, centered on Tyr-96, Thr-185, and Asp-251 result from camphor binding. This, indicates that camphor binding decreases the flexibility in these three, regions of the P-450cam molecule without altering the mean position of the, atoms involved.
About this Structure
1PHC is a Single protein structure of sequence from Pseudomonas putida with HEM as ligand. Active as Camphor 5-monooxygenase, with EC number 1.14.15.1 Full crystallographic information is available from OCA.
Reference
Crystal structure of substrate-free Pseudomonas putida cytochrome P-450., Poulos TL, Finzel BC, Howard AJ, Biochemistry. 1986 Sep 9;25(18):5314-22. PMID:3768350
Page seeded by OCA on Tue Nov 20 23:48:45 2007
