Primary Citation of Related Structures: 3KW4, 3ME6
PubMed Abstract:
Prior X-ray crystal structures of rabbit cytochrome P450 2B4 (2B4) in complexes with various imidazoles have demonstrated markedly different enzyme conformations depending on the size of the inhibitor occupying the active site. In this study, structures of 2B4 were determined with the antiplatelet drugs clopidogrel and ticlopidine, which were expected to have greater freedom of movement in the binding pocket ...
Prior X-ray crystal structures of rabbit cytochrome P450 2B4 (2B4) in complexes with various imidazoles have demonstrated markedly different enzyme conformations depending on the size of the inhibitor occupying the active site. In this study, structures of 2B4 were determined with the antiplatelet drugs clopidogrel and ticlopidine, which were expected to have greater freedom of movement in the binding pocket. Ticlopidine could be modeled into the electron density maps in two distinct orientations, both of which are consistent with metabolic data gathered with other mammalian P450 enzymes. Results of ligand docking and heme-induced NMR relaxation of drug protons showed that ticlopidine was preferentially oriented with the chlorophenyl group closest to the heme. Because of its stereocenter, clopidogrel was easier to fit in the electron density and exhibited a single orientation, which points the chlorophenyl ring toward the heme. The C(α) traces of both complexes aligned very well with each other and revealed a compact, closed structure that resembles the conformation observed in two previously determined 2B4 structures with the small molecule inhibitors 4-(4-chlorophenyl)imidazole and 1-(4-chlorophenyl)imidazole. The 2B4 active site is able to accommodate small ligands by moving only a small number of side chains, suggesting that ligand reorientation is energetically favored over protein conformational changes for binding of these similarly sized molecules. Adjusting both protein conformation and ligand orientation in the active site gives 2B4 the flexibility to bind to the widest range of molecules, while also being energetically favorable.
Related Citations:
Structure of microsomal cytochrome P450 2B4 complexed with the antifungal drug bifonazole: insight into P450 conformational plasticity and membrane interaction. Zhao, Y., White, M.A., Muralidhara, B.K., Sun, L., Halpert, J.R., Stout, C.D. (2006) J Biol Chem 281: 5973
Structure of mammalian cytochrome P450 2B4 complexed with 4-(4-chlorophenyl)imidazole at 1.9 {angstrom} resolution: Insight into the range of P450 conformations and coordination of redox partner binding. Scott, E.E., White, M.A., He, Y.A., Johnson, E.F., Stout, C.D., Halpert, J.R. (2004) J Biol Chem 279: 27294
An open conformation of mammalian cytochrome P450 2B4 at 1.6 A resolution. Scott, E.E., He, Y.A., Wester, M.R., White, M.A., Chin, C.C., Halpert, J.R., Johnson, E.F., Stout, C.D. (2003) Proc Natl Acad Sci U S A 100: 13196
Structural and thermodynamic consequences of 1-(4-chlorophenyl)imidazole binding to cytochrome P450 2B4. Zhao, Y., Sun, L., Muralidhara, B.K., White, M.A., Stout, C.D., Halpert, J.R. (2007) Biochemistry 46: 11559
Crystal Structures of Cytochrome P450 2B4 in Complex with the Inhibitor
1-Biphenyl-4-methyl-1H-imidazole: Ligand-Induced Structural Response through Alpha-Helical Repositioning Gay, S.C., Sun, L., Maekawa, K., Halpert, J.R., Stout, C.D. (2009) Biochemistry 48: 4762
Organizational Affiliation:
Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California 92093, USA. scgay@ucsd.edu
Download Mendeley
