Richard P. Swenson

Research Description:

Our research is focused primarily on the study of a family of proteins that utilize derivatives of riboflavin (vitamin B2) as essential cofactors or coenzymes for their biological activity. Our emphasis is on the investigation of the structure of the protein, its influence on the oxidation-reduction and other chemical properties of the bound flavin cofactor, and the role of the cofactor in catalysis and/or electron transfer. Flavoproteins are often an integral part of important electron transport pathways in living systems including such important processes as respiration, photosynthesis, nitrogen fixation, signal transduction, detoxification, DNA repair, and metabolism. Many of theses processes represent an important means by which chemical and photochemical energy is transformed and transported within the cell as electro-chemical potential. The flavin cofactors that participates in each of the many redox reactions catalyzed by flavoproteins are essentially the same; however, their properties and chemical reactivities are very different depending on the protein environment. It is obvious that the protein exerts a strong influence on the bound cofactor. But, how is this accomplished? Our studies are primarily focused on the determination of the major protein structural features that are responsible for the regulation of the redox and electron transferring properties of the bound flavin cofactor. A variety of systems are currently under study including flavoprotein electron transferases, the flavodoxin, and complex, multidomain flavoproteins such as cytochrome P450 reductase, part of an essential detoxification and xenobiotic-metabolizing system in mammalian cells, and nitric oxide synthetase, an enzyme important in signal transduction. Many of these proteins contain FMN-binding domains homologous to the flavodoxin, which has served as an excellent paradigm for more complex systems. Research approaches routinely used in our studies include cloning, heterologous protein expression and purification, site-directed mutagenesis, transient and steady-state kinetic analyses, redox studies, molecular modeling and protein engineering, and various types of spectroscopic methods such as UV-visible, fluorescence, circular dichroism, NMR, and Raman.

Further information as well as a list of recent publications can be found in my World Wide Web Homepage which can be found at the following URL address: http://www.biosci.ohio-state.edu/~rswenson/rswenson.html