Having successfully applied the time-resolved techniques to photocycle intermediates of photoactive yellow protein, we are extending the technique to probe the mechanism of other systems, including nitric oxide synthase and sulfite reductase. Nitric oxide synthase catalyzes the production of the physiologic signaling molecule nitric oxide. We are using a coupled spectroscopic and crystallographic approach to generate and study product-inhibited complexes and to follow oxidation states during the catalytic cycle. Combining techniques will help further our understanding of catalytic cycles in signal transduction proteins. Recent accomplishments included defining the structural chemistry of the pterin site.
Sulfite reductase helps metabolize sulfur by reducing sulfite to sulfide.
We are interested in understanding the structural relationship between the protein, its metal-containing cofactors, and its chemical function. Using our combined spectroscopic and structural technique, we are elucidating the principles that govern the unique 6-electron reaction of sulfite reductase. D.J. Tryptophan 409 controls the activity of neuronal nitric-oxide synthase by regulating nitric oxide feedback inhibition. Crane, B.R., Rosenfeld, R.J., Arvai, A.S., Ghosh, D.K., Ghosh, S., Tainer, J.A., Stuehr, D.J., Getzoff, E.D. N-terminal domain swapping and metal ion binding in nitric oxide synthase dimerization. Demchuk, E., Genick, U.K., Woo, T.T., Getzoff, E.D., Bashford, D. Protonation states and pH titration in the photocycle of photoactive yellow protein.