DNA Photolyase repairs UV-induced DNA damage using light. Leading a mutlinational collaboration, we are aiming to image photolyase performing DNA repair in real time to answer fundamental questions about enzyme function.
Our main tool for doing this is pump-probe serial femtosecond crystallography, performed at the LCLS and other XFEL facilities.
The origins of enzyme catalysis remains one of the most significant outstanding problems in biochemistry. The ability of enzymes to accelerate chemical reaction rates by factors of 1010-1020 relies on the global (nm-scale) structure and dynamics of protein structure. Mutations in residues distal from the active site, for example, often change the rate of catalysis dramatically. What role long-range structure plays, however, remains a contentious debate, with suggestions that these structures provide specific fs-timescale, µs-timescale, or a distinct lack of dynamics to facilitate chemistry. Our poor understanding is punctuated by the fact that while now we can create artificial enzymes, these catalysis perform substantially worse than their wild-type counterparts (kcat enhancements of up to only 106), and directed evolution (vs. rational design) plays a major role in the design process.