My interests lie in the area of physical chemistry and, in particular, quantum chemical calculations of molecular structure. 

Quantum Chemistry of Small Molecular Aggregates

 Quantum chemistry affords a range of tools for investigating the interactions of molecules.  My particular interest is modeling hydrogen bonding interactions between small molecules that have been arranged with fixed spatial configurations to mimic the probable interactions in larger peptide chains. 

 Biologically active peptide chains have well defined configurations.  They fold into these configurations with amazing efficiency and in ways that are not generally well understood.  Certainly, internal and solvent based hydrogen bonding interactions play a significant role in the process.  While the importance of hydrogen bonding is not disputed, including it into quantum chemical calculations is very difficult because of the enormous number of possible interactions.  Despite increases in computational power, the size of these systems still precludes direct calculations that will predict the lowest energy shape with any accuracy.  Our studies focus on modeling the interactions by placing small representative molecules (water and ammonia, for instance) is well-defined geometric relationships and performing energy minimization calculations on the assemblage.  Changing the geometry of the aggregate in a systematic way allows us to calculate an energy profile for the interactions.

 Students and I have performed these types of calculations on small peptide chains as well. The sum total of intra- and intermolecular interactions can be pictured as a vector field that exerts a force on each point along the peptide.  Of course, as the peptide chain changes its configuration, the field also changes.  In a classical approximation, this field drives the folding process in a cooperative yet nonlinear fashion.  A number of observations on the folding kinetics can be understood in the context of this model.  We are working to apply this model to specific peptide chains and calculate the resultant folding pathways.

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