A principal focus of our group is to understand the mechanism of DNA repair by the light-driven enzyme, DNA photolyase. DNA is often damaged by UV radiation that is not otherwise absorbed by the ozone layer. Photolyase is a FAD-containing (flavo)protein that uses light to drive an ultrafast electron transfer reaction between the protein and the bound DNA lesion. The transferred electron repairs the damaged DNA by an unknown mechanism. We are using ultrafast laser and biochemical techniques to unravel this mechanism. We also explore the details of substrate binding using state of the art fluorescence reporter and two photon excitation techniques.

Putative hydrogen bonding network stabilizing the FAD cofactor in the protein

A second area of interest centers around the electronic properties of flavins in flavoproteins. The redox properties of flavoenzymes are known to be sensitive to electronic interactions between the flavin cofactor and the protein host. We are studying these interactions quantitatively using Stark spectroscopy.

Transient absorption of photolyase:d(T<>T)_n complexes (n=2,5) at various mole ratios of protein:substrate