In this project, Dr. Bogdan Lesyng of the Warsaw University of Technology, will cooperate with Dr. Andrew J. McCammon of the University of Houston under the U.S.-Poland Marie Sklodowska- Curie Joint Fund to research "Quantum-Classical Dynamics Studies for Proton Transfer Process in Enzymes (MSC)." The researchers will study phospholipase A2 and either a serine proteinase or carbonic anhydrase. They will treat the enzymes as mixed quantum-classical dynamical systems. The time-dependent Schroedinger equation will be used to describe the proton dynamics. The researchers will describe the dynamics of heavy atoms by the Newtonian equations of motion with the inclusion of Hellmann-Feynman forces generated by the quantum particles. They will also simulate other quantum events in the enzyme active sites, like a nucleophilic substitution at the substrate carbonyl carbon. They plan to use a well-documented thermodynamic cycle- perturbation technique to simulate mutations of selected hydrogen bond network groups into neutral or hydrophobic groups, which they will then analyze. This project in biophysics fulfills the program objectives of advancing scientific knowledge by enabling leading experts in the U.S. and Poland to combine complementary efforts and capabilities in areas of strong mutual interest and competence on the basis of equality, reciprocity, and mutuality of benefit.