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The article presents a study to develop in vivo tooth electron paramagnetic resonance (EPR) for radiation dose estimation and screening. The study used molar teeth irradiated at varying doses. Radiation dose measurements were made using a clinical L-band EPR spectrometer. The study demonstrates the feasibility of in situ teeth measurements for immediate screening following radiation exposures.

Investigates the proton and electron transfer during the reaction of solubilized fully reduced bovine heart cyctochrome c oxidase with molecular oxygen. Time-resolved spectral changes from ligand binding and electron transfer events; Probe on kinetics and spectral changes using optical multichannel detection; Stoichiometry of proton transfer.

Provides information on a study which investigates the reaction of fully reduced cytochrome oxidase with dioxygen in the visible region (460-720nm) following photolysis of the fully reduced CO complex. Materials and methods; Summary of results; Discussion.

Studies the light-induced spectral changes in fully oxidized cytochrome c oxidase in the presence of oxygen. Spectral changes in the Soret and visible regions; Absorbance maxima; Impact of catalase addition on the initial onset of change.

Presents a sequential kinetic mechanism for the reduction of dioxygen to water by cytochrome c oxidase. Relaxation of cytochrome a3 to the reduced unliganded configuration; Binding of oxygen to cytochrome a3; Formation of a mixture of peroxy species; Formation of ferryl species; Electron redistribution of cytochrome a and CuA; Reduction of one electron.

Studies the electrocatalytic properties of succinate dehydrogenase. General observations; Cyclic voltammograms; Isosbestic point; Tunnel diode effect; Redox-driven binding and release of oxalacetate; Modeling parameters and results; Mathematical formulation.

Reports on the rapid and reversible, redox-coupled binding of an exogenous ligand to a Fe-S cluster in a protein. Transformation of [3Fe-4S] cluster generates new site for coordination; Coadsorption with neomycin or polymyxin; Equilibria and kinetics determined by voltammograms; Associative mechanism proposed for disparity in equilibrium constants.

Presents a voltammetric study of the redox kinetics of a mutant ferredoxin that appears to be kinetically defective with regard to coupled proton transfer. Electrochemical potential-reversal method; 7Fe ferredoxin I from Azotobacter vinelandii.

The reaction between bovine heart cytochrome c oxidase and dioxygen was monitored at room temperature in the visible and Soret regions following photolysis of the mixed-valence CO-bound enzyme. Time-resolved optical absorption difference spectra were collected between 50 ns and 1.7 ms by a gated multichannel analyzer. Singular value decomposition and global exponential fitting resolved three processes with apparent lifetimes of 2.2±0.5, 17±4 and 160±30 μs. The spectra of the intermediates were extracted based on a sequential kinetic mechanism and compared to the corresponding intermediate spectra observed during the reaction of the fully reduced enzyme with dioxygen. The first process is associated with a conformational change at heme a3 upon dissociation of CO from CuB+ and concomitant back-electron transfer from heme a3 to heme a. This is followed by O2 binding to heme a3 forming compound A (AM), with a spectrum identical to that observed upon O2 binding to heme a3 in the fully reduced enzyme (AR). Intermediate AM decays into PM, the spectrum of which is equivalent to that of the 607 nm form, generated upon addition of H2O2 to the oxidized enzyme at alkaline pH values (PH). However, the spectrum of PM is significantly different from the corresponding intermediate observed upon the reaction of dioxygen with the fully reduced enzyme (PR). The spectral differences between PM and PR may arise from the different number of redox equivalents at the binuclear site, with a tyrosine radical in the PM state, and tyrosine or tyrosinate in PR, or may be the consequence of a more complex reaction mechanism in the case of the fully reduced enzyme. [Copyright &y& Elsevier]