Flexibility of proteins is an integral part of their function. This motion can include reorganization of catalytic groups, loop closures, and domain movement, to name a few. The focus of our research is to understand how the dynamic and structural properties of proteins correlate with their function. The general questions that we would like to address are:

• How do changes in the structure and dynamics of enzymes contribute to catalysis, ligand specificity, and affinity?
• Are the dynamic properties responsible for substrate binding distinct from dynamic motion essential for catalysis?
• What are the roles and energetics of hydrogen bonds in substrate specificity and in catalysis?

Our primary experimental tool for approaching these questions is nuclear magnetic resonance (NMR) spectroscopy. NMR is the only experimental technique that can access molecular motion on time scales from 10^-12 - 10¹ seconds. Historically, detailed NMR studies have been restricted to peptides and small proteins. However recent advances in the field have allowed for in-depth studies of larger proteins, opening up this technique to a broad range of interesting protein dynamics questions. We are currently interested in three enzymes essential for the growth of certain bacteria.

1. VanX is a D-amino acid peptidase required by pathogenic Gram positive bacteria for survival against the antibiotic vancomycin. The limited substrate specificity of VanX is crucial to its function and therefore essential for bacterial survival. VanX recognizes a chemically narrow class of substrates, thus we are keenly interested in understanding how this enzyme discriminates against alternative, yet structurally related substrates.
2. Ribonuclease A (RNaseA) is a model enzyme that degrades single stranded ribonucleic acid. Ongoing studies focus on determining the role of us-ms timescale dynamics in the catalytic mechanism of this enzyme.
3. RhlI is a enzyme involved in the bacterial quorum sensing pathway. We are currently interested in what structural and dynamical features of RhlI are essential for its function.

In the lab, NMR spectroscopy is complemented by chemical, biochemical, and biophysical techniques to correlate dynamic information with enzyme function. Students are encouraged to devise multiple experimental approaches to address the specific question at hand. This comprehensive experimental background will enable students to become confident independent scientists.