Experimental physical chemistry: photochemistry and photobiophysics; pico- and femtosecond lasers
Awards and Academic Honors
Research Associate, Washington State University
Postdoctoral Fellow, Cornell
Transition metals are often used in the active site of proteins. Premier examples include the heme (iron porphyrin) proteins.
Hemoglobin is the best known heme protein. For a decade we, and others, have built upon that prior knowledge of basic biological function and chemical characterization to unravel in ever-increasing detail exactly what features of the protein control the interaction of the iron atom with small ligands. We use fast kinetic studies with nanosecond, picosecond, and now femtosecond lasers. The accompanying graph illustrates absorption spectra recorded at one picosecond intervals.
Our recent studies now involve other heme proteins, in particular those recently recognized as important in the many processes regulated by nitric oxide, specifically nitric oxide synthase and guanylate cyclase. In addition, we have broadened out interests to include biological systems that utilize cobalt chemistry, namely vitamin B12 and its relatives. This has led to a patentable drug invention.
Perhaps fortuitously, the model compounds have also turned out to be useful for studies of fundamental aspects of chemical reactivity in a liquid environment. This has now evolved past the stage of basic characterization into a new era in which we are pioneering the use of ultrafast laser kinetic measurements in conjunction with high-pressure to change liquid density at constant temperature and composition.
Primary Research Area
- Role of Interdomain Linker Probed by Kinetics of CO Ligation to an Endothelial Nitric Oxide Synthase Mutant Lacking the Calmodulin Binding Peptide (Residues 503-517 in Bovine). With T. Zemojtel, J. S. Scheele, P. Marásek, B. S. S. Masters, and V. S. Sharma. Biochemistry 42, 6500 (2003).
- Fluorescence Quantum Yields and Their Relation to Lifetimes of Rhodamine 6G and Fluorescein in Nine Solvents: Improved Absolute Standards for Quantum yields. With R. Wong and P. G. Seybold. Photochem. Photobiol. 75, 327 (2002).
- Kinetics of CO and NO Ligaton sith the Cys331 ? Ala Mutant of Neuronal Nitric-oxide Synthase. With J. S. Scheele, E. Bruner, T. Zemojtel, P. Marásek, L. J. Roman, B. S. S. Masters, and V. S. Sharma. J. Biol. Chem. 276, 4733 (2001).
- Enzymatic Synthesis of Caged NADP Cofactors: Aqueous NADP Photorelease and Optical Properties. With C. P. Salerno and A. P. Patron. J. Org. Chem. 65, 3971 (2000).
- Distance Dependence of Photoinduced Electron Transfer in Metalloporphyrin Dimers. With C. F. Portela, J. Brunckova, J. L. Richards, B. Schöllhorn, Y. Iamamoto, T. G. Traylor, and C. L. Perrin. J. Phys. Chem. A 103, 10540 (1999).
- Kinetics and Equilibria of Soluble Guanylate Cyclase Ligation by CO: Effect of YC-1. With V. G. Kharitonov, V. S. Sharma, and D. Koesling. Biochem. 38, 10699 (1999).
- Solvent Dependence of The Fluorescence Lifetimes of Xanthene Dyes. With G. E. Rojas, and P. G. Seybold. Photochem. Photobiol. 70, 737 (1999).