ONIOM Study of the Nonbonding Interaction of the 2PU Inhibitor With the CDK2 and CDK4 Cyclin-Dependant Kinases

We discuss in this article, the applicability of hybrid techniques [especially the our-own N-layered integrated molecular orbital and molecular mechanics (ONIOM) method] to weak chemical interactions in large systems, such as the interaction of cyclin-dependant kinases, CDK4, and CDK2, with a specific ligand (2PU) showing selectivity for CDK4. Our results show that the energies from the ONIOM calculations perfectly match our former molecular dynamics results, both for determining the amino acids which have strongest interactions with the ligand and for explaining the selectivity of 2PU towards CDK4, as compared with CDK2. We show that the ONIOM method is a good candidate for studying such interactions in large systems, even though there are still some technical and theoretical problems to solve. The calculation details will be presented together with the methodology we devised for using the ONIOM approach in such a context. (C) 2008 Wiley Periodicals, Inc. Int Quantum Chem 109: 1148-1157, 2009