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Andrew McCammon

Statistical mechanics and computational chemistry, with applications to biological systems

Most chemical reactions are carried out in solution. The solvent surroundings affect such reactions in a variety of important ways. For example, the rates of reactions between ionized molecules are often limited by the rate at which the reactants diffuse through the solvent and come into contact. Also, specific solvation effects often determine the relative free energies or stabilities of reactant, transition state, and product molecules. In our group, we study such phenomena using methods from statistical mechanics. These methods range from simulation studies, in which the equations of motion of the atoms in a model system are solved on a computer, to formal studies in which we develop and solve differential or other equations.

We also use computer models and formal techniques to examine how protein molecules function. The proteins of interest include enzymes and ligand binding proteins such as antibody molecules. The theoretical studies show, for example, how a substrate may be attracted to the active site of an enzyme by electrostatic interactions, and how the atoms within an enzyme move to participate in the catalytic transformation of a bound substrate. These methods are of practical importance in the design of new enzymes that can be synthesized by genetic engineering techniques, and in the design of new drugs that bind strongly to their receptors.

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