1cp4
From Proteopedia
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FORMATION, CRYSTAL STRUCTURE, AND REARRANGEMENT OF A CYTOCHROME P450-CAM IRON-PHENYL COMPLEX
Overview
Cytochrome P-450cam reacts with phenyldiazene (PhN = NH), or less efficiently with phenylhydrazine, to give a catalytically inactive complex with an absorption maximum at 474 nm. The prosthetic group extracted anaerobically from the inactivated protein has the spectroscopic properties of a sigma phenyl-iron complex and rearranges, on exposure to air and acid, to an approximately equal mixture of the four N-phenylprotoporphyrin IX regioisomers. The crystal structure of the intact protein complex, refined at 1.9-A resolution to an R factor of 20%, confirms that the phenyl group is directly bonded through one of its carbons to the iron atom. The phenyl ring is tilted from the heme normal by about 10 degrees in the opposite direction from that in which carbon monoxide tilts when bound to P-450cam. Camphor, the natural substrate for P-450cam, is larger than a phenyl group and hydrogen bonds to Tyr 96, the only hydrophilic residue near the active site. Electron density in the active site in addition to that contributed by the phenyl group suggests that two water molecules occupy part of the camphor binding site but are not within hydrogen-bonding distance of Tyr 96. As observed in a previous crystallographic study of inhibitor-P-450cam complexes [Poulos, T.L., & Howard, A.J. (1987) Biochemistry 26, 8165-8174], there are large changes in both the atomic positions and mobilities of the residues in the proposed substrate access channel region of the protein.(ABSTRACT TRUNCATED AT 250 WORDS)
About this Structure
1CP4 is a Single protein structure of sequence from Pseudomonas putida with and as ligands. Active as Camphor 5-monooxygenase, with EC number 1.14.15.1 Full crystallographic information is available from OCA.
Reference
Formation, crystal structure, and rearrangement of a cytochrome P-450cam iron-phenyl complex., Raag R, Swanson BA, Poulos TL, Ortiz de Montellano PR, Biochemistry. 1990 Sep 4;29(35):8119-26. PMID:2261467
Page seeded by OCA on Thu Feb 21 12:08:16 2008
