Michael K. Bowman
- (205) 348-7846
- 1007-A Shelby Hall
- NSF Postdoctoral Fellow, Argonne National Laboratory, 1976-1977
- PhD, Wayne State University, 1975
- BS, University of Kansas, 1971
- BA, University of Kansas, 1971
Prof. Bowman’s research interests center on free radical reactions in proteins and other ordered but non-crystalline environments and on the application of pulsed EPR spectroscopy to determine the structure and function of enzymes, free radicals and materials.
Pulsed Electron Paramagnetic Resonance Spectroscopy
Electron Paramagnetic Resonance (EPR) is a branch of spectroscopy that observes the spin of unpaired electrons in free radicals, excited states of molecules, metal ions and magnetic materials. Because the unpaired electrons are often the most reactive sites, EPR provides a highly selective method to study the sites that are most interesting to chemists, biologists and physicists. Pulsed EPR methods now provide ways to determine the structure, function and dynamics of proteins, free radicals and magnetic materials.
Current research involves the used of pulsed EPR to measure nanometer distances within proteins and nucleic acids to determine their structure and how their structure changes as part of their biological function. Another area of research involves measurement of the spatial distribution of radiation damage in DNA in order to understand how clusters of multiple damage sites affect the biological repair of radiation damage.
Structure and Function of Metalloproteins
Large, complex proteins catalyze a wide variety of chemical reactions at room temperature and pressure. Some reactions, such as water splitting in photosynthesis or nitrogen fixation, can only be done inefficiently in the laboratory under extreme conditions. Other enzyme reactions, such as stereospecific chemical synthesis can be done in the laboratory but with unwanted by-products that must be removed.
Current research focuses on the cytochrome bc1 complex which sits in the mitochondrial membrane and uses electron transport to pump protons across the membrane and provide the driving force for ATP synthase. Under some conditions, the cytochrome bc1 complex can be diverted into producing the toxic molecule superoxide. This production of superoxide is alleged to be involved in ageing, carcinogenesis, Type II diabetes and several genetic diseases. An important question is how this enzyme avoids producing superoxide under normal conditions and whether superoxide production can be turned on in disease causing organisms to kill them without turning it on in the host.
Defect Centers in Crystalline and Non-Crystalline Solids
The electronic, magnetic and optical properties of many materials are modified by adding small amounts of impurities or dopants. How these dopants are incorporated into the material and affect the local structure can have a major effect on its properties. EPR is one of the few spectroscopic methods capable of determining the electronic and physical structure of the dopant and in distinguishing between dopants incorporated into the material in different sites.
Current research involves studies of SiO2, TiO2 and ZrO2 crystals doped with different anions or cations. In TiO2, metal ions occupy several different interstitial sites and change the crystal from completely colorless to blue-black or grey and convert it from an insulator into a semiconductor. Once the EPR spectral parameters have been identified from careful single crystal measurements, those species can be identified in nanoparticles of TiO2 and correlated with the properties of those nanomaterials.
Tormyshev VM, Rogozhnikova OY, Bowman MK, Trukhin DV, Troitskaya TI, Vasiliev VG, Shundrin LA, Halpern HJ (2014) Preparation of Diversely Substituted Triarylmethyl Radicals by the Quenching of Tris(2,3,5,6-tetrathiaaryl)methyl Cations with C-, N-, P-, and S-Nucleophiles. European Journal of Organic Chemistry 2014 (2):371-380. doi:10.1002/ejoc.201301161
Conner KP, Schimpf AM, Cruce AA, McLean KJ, Munro AW, Frank DJ, Krzyaniak MD, de Montellano PO, Bowman MK, Atkins WM (2014) Strength of Axial Water Ligation in Substrate-Free Cytochrome P450s Is Isoform Dependent. Biochemistry 53 (9):1428-1434. doi: 10.1021/Bi401547j
Bowman MK, Krzyaniak MD, Cruce AA, Weber RT (2013) Skew projection of echo-detected EPR spectra for increased sensitivity and resolution. J Magn Reson 231 (0):117-125. doi:10.1016/j.jmr.2013.03.011
Maryasov AG, Bowman MK (2013) Bloch equations for anisotropic paramagnetic centers with spin of 1/2. J Magn Reson 233:80-86. doi:10.1016/j.jmr.2013.05.009
Trukhan SN, Yudanov VF, Tormyshev VM, Rogozhnikova OY, Trukhin DV, Bowman MK, Krzyaniak MD, Chen H, Martyanov ON (2013) Hyperfine interactions of narrow-line trityl radical with solvent molecules. J Magn Reson 233:29-36. doi:10.1016/j.jmr.2013.04.017
Epel B, Bowman MK, Mailer C, Halpern HJ (2013) Absolute oxygen R1e imaging in vivo with pulse electron paramagnetic resonance. Magnetic Resonance in Medicine. doi:10.1002/mrm.24926
Vennam PR, Fisher N, Krzyaniak MD, Kramer DM, Bowman MK (2013) A Caged, Destabilized, Free Radical Intermediate in the Q-Cycle. Chembiochem 14 (14):1745-1753. doi:10.1002/cbic.201300265
Maryasov AG, Bowman MK (2012) Spin dynamics of paramagnetic centers with anisotropic g tensor and spin of 1/2. J Magn Reson 221 (0):69-75. doi:10.1016/j.jmr.2012.05.011
Conner KP, Vennam P, Woods CM, Krzyaniak MD, Bowman MK, Atkins WM (2012) 1,2,3-Triazole-heme interactions in cytochrome P450: functionally competent triazole-water-heme complexes. Biochemistry 51 (32):6441-6457. doi:10.1021/bi300744z
Roberts AG, Cheesman MJ, Primak A, Bowman MK, Atkins WM, Rettie AE (2010) Intramolecular Heme Ligation of the Cytochrome P450 2C9 R108H Mutant Demonstrates Pronounced Conformational Flexibility of the B-C Loop Region: Implications for Substrate Binding. Biochemistry 49 (40):8700-8708
“Pulsed EPR and DFT Characterization of Radicals Produced by Photo-Oxidation of Zeaxanthin and Violaxanthin on Silica-Alumina.” Focsan, A. L.; Bowman, M. K.; Konovalova, T. A.; Molnar, P.; Deli, J.; Dixon, D. A.; Kispert, L. D. J. Phys. Chem. B 112, 1806-1819 (2008).
“Pulsed Electron Nuclear Double Resonance Studies of Carotenoid Oxidation in Cu(II)-Substituted MCM-41 Molecular Sieves.” Lawrence, J.; Focsan, A. L.; Konovalova, T. A.; Molnar, P.; Deli, J.; Bowman, M. K.; Kispert, L. D. J. Phys. Chem. B 112, 5449-5457 (2008).
“Dynamic phase shifts in nanoscale distance measurements by double electron electron resonance (DEER).” Bowman, M. K.; Maryasov, A. G. J. Mag. Res. 185, 270-282 (2007).
“A semiquinone intermediate generated at the Qo site of the cytochrome bc1 complex: importance for the q-cycle and superoxide production.” Cape, J. L.; Bowman, M. K.; Kramer, D. M. Proc. Natl. Acad. Sci. U. S. A. 104, 7887-7892 (2007).
“Simplification of Complex EPR Spectra by Cepstral Analysis.” Das, R.; Bowman, M. K.; Levanon, H.; Norris, J. R., Jr. J. Phys. Chem. A 111, 4650-4657 (2007).
“NMR Studies of Ligand Binding to P450eryF Provides Insight Into the Mechanism of Cooperativity.” Roberts AG, Diaz MD, Lampe JN, Shireman LM, Grinstead JS, Dabrowski MJ, Pearson JT, Bowman MK, Atkins WM and Campbell AP. Biochemistry 45 1673-1684 (2006).
“Two Dimensional Hyperfine Sublevel Correlation (HYSCORE) Spectroscopy: Powder Features for S=1/2, I=1.” Maryasov AG and Bowman MK. J. Mag. Res. 179, 120-135 (2006).
“Is There Stereoselectivity in Spin Trapping Superoxide by 5-Tert-Butoxycarbonyl-5-Methyl-1-Pyrroline N-Oxide?” Tsai P, Marra JM, Pou S, Bowman MK and Rosen GM. J. Org. Chem. 70, 7093-7 (2005).
“Reaction Intermediates of Quinol Oxidation in a Photoactivatable System That Mimics Electron Transfer in the Cytochrome bc1 Complex.” Cape JL, Bowman MK and Kramer DM. J. Am. Chem. Soc. 127, 4208-15 (2005).
“The Respiratory Substrate Rhodoquinol Induces Q-cycle Bypass Reactions in the Yeast Cystochrome bc1 Complex: Mechanistic and Physiological Implications.” Cape JL, Strahan JR, Lenaeus MJ, Yuknis BA, Trieu TL, Shepherd JN, Bowman MK and Kramer DM. J. Biol. Chem. 280, 34654-60 (2005).