Oxidation Kinetics of 1, 5-Dihydroflavin by Oxygen in Non-aqueous Solvent

Favaudon, Vincent

doi:10.1111/j.1432-1033.1977.tb11740.x

Cited by 24 publications

(10 citation statements)

References 52 publications

(59 reference statements)

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“…Comparison within the Flavoprotein Oxidase Family-For an efficient activation of O 2 , the reduced flavin ought to be in its anionic form (14,34,35), a condition found in most oxidases. A second prerequisite is the presence of a system that provides a H ϩ that neutralizes the developing O 2 .…”

Section: Discussionmentioning

confidence: 99%

O2 Reactivity of Flavoproteins

Saam

Rosini

Molla

et al. 2010

Journal of Biological Chemistry

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Molecular dynamics simulations and implicit ligand sampling methods have identified trajectories and sites of high affinity for O 2 in the protein framework of the flavoprotein D-amino-acid oxidase (DAAO). A specific dynamic channel for the diffusion of O 2 leads from solvent to the flavin Si-side (amino acid substrate and product bind on the Re-side). Based on this, amino acids that flank the putative O 2 high affinity sites have been exchanged with bulky residues to introduce steric constraints. In G52V DAAO, the valine side chain occupies the site that in wild-type DAAO has the highest O 2 affinity. In this variant, the reactivity of the reduced enzyme with O 2 is decreased >100-fold and the turnover number ≈1000-fold thus verifying the concept. In addition, the simulations have identified a chain of three water molecules that might serve in relaying a H ؉ from the product imino acid ‫؍‬NH 2 ؉ group bound on the flavin Reside to the developing peroxide on the Si-side. This function would be comparable with that of a similarly located histidine in the flavoprotein glucose oxidase.

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Section: Discussionmentioning

confidence: 99%

O2 Reactivity of Flavoproteins

Saam

Rosini

Molla

et al. 2010

Journal of Biological Chemistry

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“…Reduction of NpFR2 could be achieved with a range of mild reducing agents such as sodium dithionite, sodium cyanoborohydride, glutathione (GSH) and dithiothreitol (DTT). The fluorescence properties of NpFR2 as well as the kinetics of re-oxidation suggest that NpFR2 follows a similar sensing mechanism to that of riboflavin and NpFR1, 19,23 confirming that the TPP tag has not affected these properties. 1b).…”

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confidence: 80%

Mitochondrially targeted redox probe reveals the variations in oxidative capacity of the haematopoietic cells

et al. 2015

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Both oxidative stress and mitochondrial dysfunction play roles in a myriad of pathological conditions. There is therefore a need for tools that possess the ability to measure the dynamics of oxidative capacity within the mitochondria, particularly those that can measure reversible changes. Here, we report a mitochondrially-targeted fluorescent redox sensor NpFR2, which can reversibly measure changes in the mitochondrial redox environment. The probe has been used to report on variations in oxidative capacity of the haematopoietic cells in bone marrow, thymus and spleen.

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“…The validity of the procedure was verified by a few direct measurements using the oxidation reaction of tetraacetylriboflavin [24].…”

Section: Preparation Of Samplesmentioning

confidence: 91%

Viscosity‐dependent energy barriers and equilibrium conformational fluctuations in oxygen recombination with hemerythrin

Lavalette

Tétreau

1988

European Journal of Biochemistry

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The recombination kinetics of photo-dissociated oxyhemerythrin (Sipunculus nudus) have been investigated between 298 K and 90 K. Fast geminate recombinations compete with oxygen escape into the solvent, from which a subsequent slower bimolecular rebinding takes place. In phosphate buffer @H 7.7) at 278 K, the fast and slow processes are exponential and have comparable amplitudes. Whereas the oxygen escape rate rapidly decreases upon increasing the viscosity, the inward rate from the solvent is found to be independent of viscosity, up to about 50 CP (50 mPa . s). The data suggest that a Brownian-motion-driven displacement of one or several side-chain residues is implied in oxygen escape from within the protein and also that hemerythrin undergoes a conformational change in the deoxy state.At higher viscosities and lower temperature only the geminate phase is observed and the kinetics progressively depart from an exponential. Below about 130 K, the kinetics resemble those reported in the literature for heme proteins. They are consistent with a temperature-independent non-equilibrium frozen distribution of conformational substates. However, between 190 K and 130 K, the profile of the kinetics is invariant on a log/ log plot and the results simply differ by a translation along the log t axis. It is shown that this property is expected only for a temperature-dependent distribution of substates in a Boltzmann equilibrium. From room temperature, where rebinding is exponential, down to the 'freezing' temperature, the geminate recombinations display a variety of kinetic laws. It can be shown, however, that for a broad class of substate distributions, the initial slope of the kinetic plot follows an Arrhenius relationship. The activation energy is equal to that of the exponential rate constant measured at high temperature. This result establishes the conditions under which protein data obtained from low-temperature kinetics can be extrapolated to physiological temperature.A protein at thermodynamic equilibrium is subject to transient fluctuations. More than ten years ago, it had been pointed out that volume fluctuations 'if concentrated in one area would produce cavities or channels in the proteins sufficient to allow entry of solvent or probe molecules' [l] and the importance of viscosity-dependent structural fluctuations in enzyme catalysis had been emphasized [2]. A great deal of our present knowledge on protein conformational fluctuations comes from chemical relaxation experiments on oxygen-carrying heme proteins. It is well known that hemoglobin or myoglobin undergo important spectroscopic changes upon binding a ligand (generally oxygen or carbon monoxide) and that ligand dissociation can be triggered, with a relatively high yield, by a light pulse. The subsequent rebinding events can be followed accurately using fast optical absorption spectroscopy.A unique property of heme proteins is that their prosthetic group, the heme, exhibits the elementary reaction of ligand binding in the isolated state. In hemoglobin or myo...

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Oxidation Kinetics of 1, 5-Dihydroflavin by Oxygen in Non-aqueous Solvent

Cited by 24 publications

References 52 publications

O2 Reactivity of Flavoproteins

O2 Reactivity of Flavoproteins

Mitochondrially targeted redox probe reveals the variations in oxidative capacity of the haematopoietic cells

Viscosity‐dependent energy barriers and equilibrium conformational fluctuations in oxygen recombination with hemerythrin

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