Structural dynamics of the cooperative binding of organic molecules in the human Cytochrome P450 3A4 (CYP3A4)

MEDI 202

Dan Fishelovitch, danfishl@post.tau.ac.il, Department of Human Genetics, Tel-Aviv university, Ramat-Aviv Haim Levanon st, Tel-Aviv, 61390, Israel, Carina Hazan, Institute of Chemistry and the Lise-Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel, Sason Shaik, sason@yfaat.ch.huji.ac.il, the department of organic chemistry and the lise meitner-minerva center of computational chemistry, Hebrew University, Jerusalem 91904, Israel, Haim Wolfson, wolfson@tau.ac.il, Computer Science, Tel Aviv University, Tel Aviv, Israel, and Ruth Nussinov, ruthn@ncisgi.ncifcrf.gov, Basic Research Program - Macromolecular Structure, SAIC Frederick, Inc. NCI, 1050 Boyles Street, PO Box B, Frederick, MD 21702.
Cytochrome P450 3A4 is a key enzyme responsible for the metabolism of 50% of all orally administered drugs which exhibit an intriguing kinetic behavior typified by sigmoidal dependence of reaction velocity vs. substrate concentration. The mechanism of cooperative binding is yet unclear. In order to better understand the mechanism of cooperative binding we carried out molecular dynamics simulations for two enzymatic conformers and examined the differences between the substrate-free and the bound enzymes, with one and two substrates. Our results indicate that the effector substrate interacts both with the active substrate and with the enzyme, and this interaction results in side chain reorientation with relatively minor long-range effects. In accord with experiment, we find that F304, in the interface between the active and effector binding sites is a key residue in the mechanism of cooperative binding. When R212 strongly interacts with F304, it counteracts the effector's impact on the enzyme.
 

Poster Session
7:00 PM-9:00 PM, Sunday, August 19, 2007 BCEC -- Exhibit Hall - B2, Poster

Sci-Mix
8:00 PM-10:00 PM, Monday, August 20, 2007 BCEC -- Exhibit Hall - B2, Sci-Mix

Division of Medicinal Chemistry

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007