Frank M. Raushel
Professor of Chemistry
Professor of Biochemistry and Biophysics
Ph. D., University of Wisconsin
Contact
Information:
Department of Chemistry
Texas A&M University
College Station, TX 77842
Phone:
(979) 845-3373
Fax: (979) 845-9452
raushel@chem.tamu.edu
Enzymes catalyze a remarkable variety of chemical reactions with extremely high rate enhancements and very selective substrate specificity. The research efforts in our laboratory are directed towards a more complete understanding of the fundamental principles involved in enzyme-catalyzed chemistry and the dependence on protein structure. The pursuit of this information will provide the framework for the rational and combinatorial redesign of these complex molecules in an effort to exploit and develop the properties of enzyme active sites for a variety of chemical, biological, and medicinal uses. The techniques that we are using to solve these problems include steady-state and stopped-flow kinetics, NMR and EPR spectroscopy, X-ray crystallography, and the synthesis of inhibitors and suicide substrates. We are also using recombinant DNA methods to construct new proteins with novel catalytic properties. These efforts are currently being directed to the reactions catalyzed by carbamoyl phosphate synthetase, phosphotriesterase, and dihydroorotase.
The phosphotriesterase enzyme catalyzes the detoxification of organophosphate insecticides. We recently discovered that the active site of this protein consists of a unique binuclear metal center. We are now investigating the structure and properties of this metal center as a research tool for the evolution of enzyme structure and function. Carbamoyl phosphate synthetase catalyzes the formation of the key precursor for the biosynthesis of arginine and pyrimidine nucleotides. The complex heterodimeric protein contains three independent active sites connected by an internal molecular tunnel of 100 Å in length. It now appears that this protein operates as a unique molecular machine where the unstable intermediates are transported from one active site to the next via the controlled diffusion through the intermolecular tunnel. Dihydroorotase (DHO) catalyzes the reversible hydrolysis of the amide bond within dihydroorotate. This metabolic intermediate is required for the biosynthesis of pyrimidine nucleotides. DHO contains a binuclear metal center and is related to phosphotriesterase via divergent evolution
X. Huang and F. M. Raushel, "An Engineered Blockage within the Ammonia Tunnel in Carbamoyl Phosphate Synthetase Prevents of the Use of Glutamine as a Substrate but not Ammonia" Biochemistry 39, 3240-3247 (2000).
B. W. Miles and F. M. Raushel, "Synchronization of the Three Reaction Centers within Carbamoyl Phosphate Synthetase" Biochemistry 39, 5051-5056 (2000).
H. Shim and F. M. Raushel, "Self-Assembly of the Binuclear Metal Center of Phosphotriesterase" Biochemistry 39, 7357-7364 (2000).
F. Wu, W.-S. Li, M. Chen-Goodspeed, M. Sogorb, and F. M. Raushel, "Rationally Engineered Mutants of Phosphotriesterase for Preparative Scale Isolation of Chiral Organophosphates" Journal of American Chemical Society, 122, 10206-10207 (2000).
M. Chen-Goodspeed, M. A. Sogorb, F. Wu, and F. M. Raushel, "Enhancement, Relaxation, and Reversal of the Stereoselectivity for Phosphotriesterase by Rational Evolution of Active Site Residues" Biochemistry 40, 1332-1339 (2001).
J. B. Thoden, G. N. Phillips, T. M. Neal, F. M. Raushel, H. M. Holden, "Molecular Structure of Dihydroorotase: A Paradigm for Catalysis Through the Use of a Binuclear Metal Center" Biochemistry 40, 6989-6997 (2001).
W. Li, Y. Li, C. M. Hill, K. T. Lum, and F. M. Raushel, "Enzymatic Synthesis of Chiral Organophosphothioates from Prochiral Precursors" Journal of American Chemical Society, 124, 3498-3499 (2002).
