R. DAVID BRITT

Professor and Chair

Email: britt@chem.ucdavis.edu

Physical Chemistry

B.S., North Carolina State University, 1978. M.A.; Ph.D., University of California, Berkeley, 1980; 1988. Dreyfus Award, 1989-94. Appointed to faculty, UC Davis, 1989-.

Research Interests

The Britt group's research focuses on the biological chemistry enabled by transition metals and amino acid and cofactor radicals. Much of our work is directed towards photosynthesis, particularly the Photosystem II oxygen evolving complex, which harnesses the energy of visible light photons to split water, producing molecular oxygen and biologically activated electrons and protons. This chemistry occurs in a catalytic complex containing a tetranuclear cluster of high valence manganese ions and a photogenerated tyrosine amino acid radical, along with essential Cl^- and Ca²⁺ cofactors. Other current research interests include the function of Photosystem I, cytochrome c oxidase, manganese catalase, and the biological roles of vanadium. We are also exploring the binding of metal ions to nucleic acids and how such metal centers are involved in ribozyme catalytic function.

Our approach to understanding these complex biological metal and radical centers utilizes sophisticated electron paramagnetic resonance (EPR) spectroscopies. Pulsed EPR methods such as electron spin echo envelope modulation (ESEEM) and electron spin echo - electron nuclear double resonance (ESE-ENDOR) allow us to probe the magnetic environment of metal and radical centers with high sensitivity to magnetic nuclei such as ¹H, ²H, ¹⁴N, ¹⁵N, ¹³C, ⁵⁵Mn, and ⁵¹V. These spectroscopies combined with site directed mutagenesis and selective isotopic labelling methods provide extremely powerful structural probes. Laser initiated electron transfer is being dynamically probed using time resolved pulsed EPR spectroscopy with 10 ns time resolution. EPR relaxation measurements are providing additional structural and dynamics information. Parallel polarization EPR spectroscopy is producing new insights into integer spin paramagnetic states of biological metal clusters.

Publications

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Lorigan, G. A., Britt, R. D., Kim, J. H., and Hille, R. (1994) Electron Spin Echo Envelope Modulation Spectroscopy of the Molybdenum Center of Xanthine Oxidase. Biochim. Biophys. Acta 1185, 284-294.

Tang, X.-S., Diner, B. A., Larsen, B. S., Gilchrist, M. L., Lorigan, G. A., and Britt, R. D. (1994) Identification of Histidine at the Catalytic Site of the Photosynthetic Oxygen Evolving Complex. Proc. Natl. Acad. Sci. U.S.A. 91, 704- 708.

Lorigan, G. A. and Britt, R. D. (1994) Temperature Dependent Pulsed EPR Relaxation Studies of the S2 State Multiline Signal of the Photosynthetic Oxygen-Evolving Complex. Biochemistry 33, 12072-12076.

Sturgeon, B. E., Ball, J. A., Randall, D. W., and Britt, R. D. (1994) ⁵⁵Mn Electron Spin Echo ENDOR of Mn2+ Complexes. J. Phys.. Chem. 98, 12871-12883.

Britt, R. D., Tang, X.-S., Gilchrist, M. L., Lorigan, G. A., Larsen, B. S., and Diner, B. A. (1994) Histidine at the Catalytic Site of the Photosynthetic Oxygen-Evolving Complex. Biochemical Society Transactions 22, 343-347.

Gilchrist, M. L., Ball, J. A., Randall, D. W., and Britt, R. D. (1995) Proximity of the Manganese Cluster of Photosystem II to the Redox Active Tyrosine Yz Proc. Natl. Acad. Sci. U.S.A. 92, 9545-9549.

Randall, D. W., Sturgeon, B. E., Ball, J. A., Lorigan, G. A., Chan, M. K., Klein, M. P., Armstrong, W. H., and Britt, R. D. (1995) ESE-ENDOR of a Mixed Valence Mn(III)Mn(IV) Complex: Comparison with the Mn Cluster of the Photosynthetic Oxygen Evolving Complex. J. Am. Chem. Soc. 117, 11780-11789.

Tang, X.-S., Peloquin, J. M., Lorigan, G. A., Britt, R. D., and Diner, B. A. (1995) The Binding Environment of the Reduced Primary Quinone Electron Acceptor, QA of PSII. In Photosynthesis: from Light to Biosphere (ed. P.Mathis) Kluwer Academic Publishers, Amsterdam, vol I, pp. 775-778.

Britt, R. D., Randall, D. W., Ball, J. A., Gilchrist, M. L., Force,D. A., Sturgeon, B. E., Lorigan, G. A., Tang, X.-S., Diner, B. A., Klein,M. P., Chan, M. K., and Armstrong, W. H. (1995) Electron Spin Echo - ENDOR Studies of the Tyrosine Radicals and the Manganese Cluster of Photosystem II. In Photosynthesis: from Light to Biosphere (ed. P. Mathis) Kluwer AcademicPublishers, Amsterdam, vol II, pp. 223-228.

Diner, B. A., Tang, Zheng, M., Dismukes, G. C., Force, D. A., Randall, D. W., and Britt, R. D. (1995) Environment and Function of the Redox Active Tyrosines of Photosystem II. In Photosynthesis: from Light to Biosphere(ed. P. Mathis) Kluwer Academic Publishers, Amsterdam, vol II, pp. 229-234.

Force, D. A., Randall, D. W., Britt, R. D., Tang, X.-S., and Diner, B. A. (1995) ESE-ENDOR Study of Hydrogen Bonding to the Tyrosine Radicals YD and YZ of Photosystem II., J. Am. Chem. Soc. 117, 12643-12644.

Britt, R. D. (1995) Electron Spin Echo Methods in Photosynthesis Research.In Advances in Photosynthesis: Biophysical Techniques in Photosynthesis(eds. A. J. Hoff and J. Amesz) Kluwer Academic Publishers, Amsterdam, pp.235-253.

Tang, X.-S., Randall, D. W., Force, D. A., Diner, B. A. and Britt, R.D. (1996) Manganese-Tyrosine Interaction in the Photosystem II Oxygen Evolving Complex. J. Am. Chem. Soc. 118, 7638-7639.

Britt, R. D. (1996) Oxygen Evolution. In Advances in Photosynthesis: Oxygenic Photosynthesis, The Light Reactions (eds. C. Y. Yocum and D. Ort) Kluwer Academic Publishers, Amsterdam, pp.137-164.

Randall, D. W., Gelasco, A., Pecoraro, V. L., and Britt, R. D. (1997) ESE-ENDOR and ESEEM Characterization of Water and Methanol Ligation to a Dinuclear Mn(III)Mn(IV) Complex. J. Am. Chem. Soc. 119, 4481-4491.

Campbell, K. A., Peloquin, J. M., Diner, B. A., Tang, X.-S., Chisholm, D. A., and Britt, R. D. (1997) The tau-Nitrogen of D2 Histidine 189 isthe Hydrogen Bond Donor to the Tyrosine Radical YD of Photosystem II. J.Am. Chem. Soc. 119, 4787-4788.

Farrar, C. T., Gerfen, G. J., Griffin, R. G., Force, D. A., and Britt, R. D. (1997) Electronic Structure of the YD Tyrosyl Radical in Photosystem II: A High Frequency EPR Spectroscopy and Density Functional Theoretical Study. J. Phys. Chem. 101, 6634-6641.

Stemmler, T. L., Sturgeon, B. E., Randall, D. W., Britt, R. D., and Penner-Hahn, J. E. (1997) Spectroscopic Characterization of Inhibitor Interactions with the Mn(III)/Mn(IV) Core in Lactobacillus plantarum Manganese Catalase. J. Am. Chem. Soc. 119, 9215-9225.

Force, D. A., Randall, D. W., and Britt, R. D. (1997) Proximity of Acetate, Manganese, and Exchangeable Deuterons to Tyrosine YZ in Acetate-Inhibited Photosystem II Membranes: Implications for the Direct Involvement of YZ in Water-Splitting. Biochemistry 36, 12062-12070.

Dole, F., Diner, B. A., Hoganson, C., Babcock, G. T., and Britt, R. D. (1997) Determination of the Electron Spin Density on the Phenolic Oxygen of Tyrosine Radical YD of Photosystem II. J. Am. Chem. Soc. 119, 11540-11541.

Campbell, K. A., Peloquin, J. M., Pham, D. P, Debus, R. J., and Britt, R. D. (1998) Parallel Polarization EPR Detection of an S1-State "Multiline'' EPR Signal in Photosystem II Particles from Synechocystis sp. PCC 6803. J. Am. Chem. Soc. 120, 447-448.

Grant, C.F., J.A. Ball, B. Hamstra, V. Pecoraro, and R.D. Britt. (1998) ⁵¹V ESE-ENDOR studies of oxovanadium(IV) complexes: Investigation of the nuclear quadrupole interaction. J. Phys. Chem. B, 102, 8145-8150.

Randall, D.W., M.K. Chan, W.H. Armstrong, and R.D. Britt. (1998) Pulsed ¹H and ⁵⁵MN ENDOR studies of dinuclear Mn(III)Mn(IV) model complexes. J. Mol. Phys. 95, 1283-1294.

Diner, B.A., D.A. Force, D.W. Randall, and R.D. Britt. (1998) Hydrogen bonding, solvent exchange, and coupled proton and electron transfer in the oxidation and reduction of redox-active tyrosine Y_Z in Mn-depleted core complexes of photosystem II. Biochemistry, 37, 17931-17943.

Peloquin, J.M., K.A. Campbell, and R.D. Britt. (1998) ⁵⁵Mn pulsed ENDOR demonstrates that the photosystem II "split" EPR signal arises from a magnetically-coupled mangano-tyrosyl complex. J. Am. Chem. Soc., 120, 6840-6841.

Campbell, K.A., W. Gregor, D.P. Pham, J.M. Peloquin, R.J. Debus, and R.D. Britt. (1998) The 23 and 17 kDa extrinsic proteins of photosystem II modulate the magnetic properties of the S₁-state manganese cluster. Biochemistry, 37, 5039-5045.

Britt, R.D., D.A. Force, K.A. Campbell, D.W. Randall, L.M. Gilchrist, Jr., K.L. Clemens, D.M. Gingell, J.M. Peloquin, D.P. Pham, and R.J. Debus. (1998) "Progress in characterization of the photosystem II oxygen evolving complex using advanced EPR methods." In Spectroscopic Methods in Bioinorganic Chemistry. E.I. Solomon and K.O. Hodgson, eds., Oxford University Press, pp. 272-285.

Elliot, S.J., D.W. Randall, R.D. Britt, and S.I. Chan. (1998) Pulsed EPR studies of particulate methane monooxygenase from Methylococcus capsulatus (bath): Evidence for histidine ligation. J. Am. Chem. Soc., 120, 3247-3248.

Force, D. A., Randall, D. W., Lorigan, G. A., Clemens, K. L., and Britt, R. D. (1998) ESEEM Studies of Alcohol Binding to the Manganese Cluster of the Oxygen Evolving Complex of Photosystem II. J. Am. Chem. Soc. 120, 13321-13333.

Messinger, J., Robblee, J. H., Fernandez, C., Cinco, R. M., Visser, H., Bergmann, U., Glatzel, P., Cramer, S. P., Campbell, K. A., Peloquin, J. M., Britt, R. D., Sauer, K., Yachandra, V. K. and Klein, M. P. (1998) Oxidation States and Structure of the Manganese Cluster in the S0 Stateof the Oxygen Evolving Complex. In Photosynthesis: Mechanisms and Effects, Vol. II; (ed. G. Garab) Kluwer Academic: Dordrecht, The Netherlands, pp. 785-788.

Gregor, W. and Britt, R. D. (1998) Characterization of an S1-State Specific EPR Multiline Signal of the Photosystem II Manganese Cluster. In Photosynthesis: Mechanisms and Effects, Vol. II; (ed. G. Garab) Kluwer Academic: Dordrecht, The Netherlands, pp. 1299-1302.

Debus, R. J., Campbell, K. A., Pham, D. P., Hays, A.-M. A., Peloquin, J. M. and Britt, R. D. (1998) Influence of D1-Glu189 on the Properties of Yz and the Manganese Cluster in Photosystem 2. In Photosynthesis: Mechanisms and Effects, Vol. II; (ed. G. Garab) Kluwer Academic: Dordrecht, The Netherlands, pp. 1375-1378.

Peloquin, J. M., Tang, X.-S., Diner, B. A., and Britt, R. D. (1999) An Electron Spin Echo Envelope Modulation (ESEEM) Study of the QA Binding Pocket of PSII Reaction Centers from Spinach and Synechocystis. Biochemistry 38, 2057-2067.

Campbell, K. A., Yikilmaz, E., Grant, C. V., Gregor, W., Miller, A. F. and Britt, R. D. (1999) Parallel Polarization EPR Characterization of the Mn(III) Center of Oxidized Manganese-Superoxide Dismutase. J. Am. Chem. Soc. 121, 4714-4715.

Morrissey, S. R., Horton, T. E., Grant, C. V., Hoogstraten C, Britt, R. D. and DeRose V. J. (1999) Mn2+ Nitrogen Interactions in RNA Probed by Electron Spin Echo Envelope Modulation Spectroscopy: Application to the Hammerhead Ribozyme. J. Am. Chem. Soc. 121, 9215-9218.

Grant, C. V., Cope, W., Ball, J. A., Maresch, G. G., Gaffney, B. J., Fink, W. H., and Britt, R. D. (1999) Electronic Structure of the Aqueous Vanadyl Ion Probed by 9 and 94 GHz EPR and Pulsed ENDOR Spectroscopies and Density Functional Theory Calculations. J. Phys. Chem., in press.

Britt, R. D., Peloquin, J. M., and Campbell, K. A. (2000) Pulsed and Parallel Polarization EPR Characterization of the Manganese Cluster of the Photosystem II Oxygen Evolving Complex. Annual Reviews of Biophysics and Biomolecular Structure, v29. in press

Grant, C. V., Geiser-Bush, K. M., Cornman, C. R., and Britt, R. D. (1999) Probing the Molecular Geometry of Five-Coordinate Vanadyl Complexes with Pulsed ENDOR. Inorg. Chem., in press.

Britt, R. D. (1999) Oxygen Production. invited article in the Encyclopedia of Life Sciences, Macmillan Reference Limited, London. in press.

Debus, R. J., Campbell, K. A., Peloquin, J. M., Pham, D. P., and Britt, R. D. (1999) Histidine 332 of the D1 Polypeptide Modulates the Magnetic and Redox Properties of the Manganese Cluster and the Tyrosine Yz in Photosystem II. Biochemistry, in press.

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