R David Britt

Learn More
Electron paramagnetic resonance (EPR) spectroscopy has often played a crucial role in characterizing the various cofactors and processes of photosynthesis, and photosystem II and its oxygen evolving chemistry is no exception. Until recently, the application of EPR spectroscopy to the characterization of the oxygen evolving complex (OEC) has been limited to(More)
Photosystem II uses visible light to drive the oxidation of water, resulting in bioactivated electrons and protons, with the production of molecular oxygen as a byproduct. This water-splitting reaction is carried out by a manganese cluster/tyrosine radial ensemble, the oxygen -evolving complex. Although conventional continuous-wave, perpendicular(More)
The pulsed electron paramagnetic resonance (EPR) methods of electron spin echo envelope modulation (ESEEM) and electron spin echo-electron nuclear double resonance (ESE-ENDOR) are used to investigate the structure of the Photosystem II oxygen-evolving complex (OEC), including the paramagnetic manganese cluster and its immediate surroundings. Recent(More)
An S1-state parallel polarization "multiline" EPR signal arising from the oxygen-evolving complex has been detected in spinach (PSII) membrane and core preparations depleted of the 23 and 17 kDa extrinsic polypeptides, but retaining the 33 kDa extrinsic protein. This S1-state multiline signal, with an effective g value of 12 and at least 18 hyperfine lines,(More)
Previously, using acetate deuterated in the methyl hydrogen positions, we showed that acetate binds in close proximity to the Mn cluster/Y(.)(z) tyrosine dual spin complex in acetate-inhibited photosystem II (PSII) preparations exhibiting the "split" EPR signal arising from the S(2)-Y(.)(z) interaction [Force, D. A.; Randall, D. W.; Britt, R. D.(More)
The role of nitric oxide (NO) in the host response to infection and in cellular signaling is well established. Enzymatic synthesis of NO is catalyzed by the nitric oxide synthases (NOSs), which convert Arg into NO and citrulline using co-substrates O2 and NADPH. Mammalian NOS contains a flavin reductase domain (FAD and FMN) and a catalytic heme oxygenase(More)
The possibility of nitrogen ligation to the Mn in the oxygen-evolving complex from photosystem II was investigated with electron paramagnetic resonance (EPR) and electron spin echo envelope modulation (ESEEM) spectroscopies using 14N- and 15N-labeled preparations. Oxygen-evolving preparations were isolated from a thermophilic cyanobacterium, Synechococcus(More)
Aspartate 170 of the D1 polypeptide provides part of the high-affinity binding site for the first Mn(II) ion that is photooxidized during the light-driven assembly of the (Mn)(4) cluster in photosystem II [Campbell, K. A., Force, D. A., Nixon, P. J., Dole, F., Diner, B. A., and Britt, R. D. (2000) J. Am. Chem. Soc. 122, 3754-3761]. However, despite a wealth(More)
Multifrequency electron spin-echo envelope modulation (ESEEM) spectroscopy is used to ascertain the nature of the bonding interactions of various active site amino acids with the Mn ions that compose the oxygen-evolving cluster (OEC) in photosystem II (PSII) from the cyanobacterium Synechocystis sp. PCC 6803 poised in the S(2) state. Spectra of natural(More)
Organisms are adapted to the relentless cycles of day and night, because they evolved timekeeping systems called circadian clocks, which regulate biological activities with ~24-hour rhythms. The clock of cyanobacteria is driven by a three-protein oscillator composed of KaiA, KaiB, and KaiC, which together generate a circadian rhythm of KaiC phosphorylation.(More)