flavin-adenine-dinucleotide has been researched along with stannic-oxide* in 2 studies
2 other study(ies) available for flavin-adenine-dinucleotide and stannic-oxide
| Article | Year |
|---|---|
Proton-coupled electron transfer of flavodoxin immobilized on nanostructured tin dioxide electrodes: thermodynamics versus kinetics control of protein redox function.
In this paper, we report a spectroelectrochemical investigation of proton-coupled electron transfer in flavodoxin D. vulgaris Hildenborough (Fld). Poly-L-lysine is used to promote the binding of Fld to the nanocrystalline, mesoporous SnO(2) electrodes. Two reversible redox couples of the immobilized Fld are observed electrochemically and are assigned by spectroelectrochemistry to the quinone/semiquinone and semiquinone/hydroquinone couples of the protein's flavin mononucleotide (FMN) redox cofactor. Comparison with control data for free FMN indicates no contamination of the Fld data by dissociated FMN. The quinone/semiquinone and semiquinone/hydroquinone midpoint potentials (E(q/sq) and E(sq/hq)) at pH 7 were determined to be -340 and -585 mV vs Ag/AgCl, in good agreement with the literature. E(q/sq) exhibited a pH dependence of 51 mV/pH. The kinetics of these redox couples were studied using cyclic voltammetry, cyclic voltabsorptometry, and chronoabsorptometry. The semiquinone/quinone reoxidation is found to exhibit slow, potential-independent but pH-sensitive kinetics with a reoxidation rate constant varying from 1.56 s(-)(1) at pH 10 to 0.0074 s(-)(1) at pH 5. The slow kinetics are discussed in terms of a simple kinetics model and are assigned to the reoxidation process being rate limited by semiquinone deprotonation. It is proposed that this slow deprotonation step has the physiological benefit of preventing the undesirable loss of reducing equivalents which results from semiquinone oxidation to quinone. Topics: Crystallization; Electrodes; Electron Transport; Flavin Mononucleotide; Flavin-Adenine Dinucleotide; Flavodoxin; Hydrogen-Ion Concentration; Hydroquinones; Kinetics; Microchemistry; Oxidation-Reduction; Polylysine; Protons; Quinones; Thermodynamics; Tin Compounds | 2004 |
Site-specific immobilization of flavin adenine dinucleotide on indium/tin oxide electrodes through flavin adenine amino group.
A Mannich-type reaction was used to attach flavin adenine dinucleotide (FAD) covalently to aminosilane derivatized indium/tin oxide-coated glass plates. The aminosilane was activated with formaldehyde to give an intermediate that attached specifically to the adenine amino group of FAD. The presence of the intermediate also was demonstrated by coupling hydroquinone to the formaldehyde activated support. The immobilized FAD and hydroquinone were characterized by cyclic or differential pulse voltammetry. The immobilized FAD was shown to reduce the overpotential for NADH oxidation by 180 mV. In keeping with results for FAD on glassy carbon, FAD attached to indium/tin oxide at the adenine amino group did not lead to reconstitution of activity with apoglucose oxidase. Topics: Apoenzymes; Chemical Phenomena; Chemistry; Electrochemistry; Electrodes; Flavin-Adenine Dinucleotide; Glucose Oxidase; Hydroquinones; Indium; Mannich Bases; NAD; Oxidation-Reduction; Spectrometry, Fluorescence; Tin; Tin Compounds | 1985 |