title: Structure of a substrate complex of mammalian cytochrome P450 2C5 at 2.3 A resolution: evidence for multiple substrate binding modes.
abstract: The structure of rabbit microsomal cytochrome P450 2C5/3LVdH complexed with a substrate, 4-methyl-N-methyl-N-(2-phenyl-2H-pyrazol-3-yl)benzenesulfonamide (DMZ), was determined by X-ray crystallography to 2.3 A resolution. Substrate docking studies and electron density maps indicate that DMZ binds to the enzyme in two antiparallel orientations of the long axis of the substrate. One orientation places the principal site of hydroxylation, the 4-methyl group, 4.4 A from the heme Fe, whereas the alternate conformation positions the second, infrequent site of hydroxylation at >5.9 A from the heme Fe. Comparison of this structure to that obtained previously for the enzyme indicates that the protein closes around the substrate and prevents open access of water from bulk solvent to the heme Fe. This reflects a approximately 1.5 A movement of the F and G helices relative to helix I. The present structure provides a complete model for the protein from residues 27-488 and defines two new helices F' and G'. The G' helix is likely to contribute to interactions of the enzyme with membranes. The relatively large active site, as compared to the volume occupied by the substrate, and the flexibility of the enzyme are likely to underlie the capacity of drug-metabolizing enzymes to metabolize structurally diverse substrates of different sizes.
authors.affiliation: Department of Molecular and Experimental Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, MEM-255, La Jolla, California 92037, USA.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Wester
authors.forename: Eric F
authors.initials: EF
authors.lastname: Johnson
authors.forename: Cristina
authors.initials: C
authors.lastname: Marques-Soares
authors.forename: Patrick M
authors.initials: PM
authors.lastname: Dansette
authors.forename: Daniel
authors.initials: D
authors.lastname: Mansuy
authors.forename: C David
authors.initials: CD
authors.lastname: Stout
mesh_terms: D018360:Crystallography, X-Ray; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry*; D000072467:Cytochrome P450 Family 2; D004583:Electrons; D006418:Heme / Q000737:chemistry; D006801:Humans; D007093:Imidazoles / Q000737:chemistry*; D007501:Iron / Q000737:chemistry; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D013255:Steroid 21-Hydroxylase / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D007093:Imidazoles; D014867:Water; D006418:Heme; C050486:5-amino-1,2-dimethylimidazole; D003577:Cytochrome P-450 Enzyme System; D007501:Iron; C065407:CYP2C5 protein, Oryctolagus cuniculus; D000072467:Cytochrome P450 Family 2; D013255:Steroid 21-Hydroxylase