The effect of pH and ligand exchange on the redox properties of blue copper proteins

Canters, Gerard W.; Kolczak, Urszula; Armstrong, Fräser A.; Jeuken, Lars J. C.; Camba, Raúl; Sola, Marcó

doi:10.1039/b003822i

Cited by 42 publications

(41 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The occurrence of a three-coordinated Cu species is not unprecedented. [39][40][41][42] Type-1 Cu sites have a tendency to change their coordination from four to three upon reduction, and the same may apply to type-2 sites like the IRS in our case. It is conceivable that binding of a neutral fourth ligand, like a water molecule, by the threecoordinate reduced copper is thermodynamically still a pos- Squares depict EM values as obtained from the PFV measurements at saturating nitrite concentrations (10 mM between pH 5 and 5.6, 50 mM between pH 5.8 and 6.2, 100 mM above pH 6.2).…”

Section: Discussionmentioning

confidence: 60%

Protein Film Voltammetry of Copper-Containing Nitrite Reductase Reveals Reversible Inactivation

et al. 2007

Self Cite

View full text Add to dashboard Cite

The Cu-containing nitrite reductase from Alcaligenes faecalis S-6 catalyzes the one-electron reduction of nitrite to nitric oxide (NO). Electrons enter the enzyme at the so-called type-1 Cu site and are then transferred internally to the catalytic type-2 Cu site. Protein film voltammetry experiments were carried out to obtain detailed information about the catalytic cycle. The homotrimeric structure of the enzyme is reflected in a distribution of the heterogeneous electron-transfer rates around three main values. Otherwise, the properties and the mode of operation of the enzyme when it is adsorbed as a film on a pyrolytic graphite electrode are essentially unchanged compared to those of the free enzyme in solution. It was established that the reduced type-2 site exists in either an active or an inactive conformation with an interconversion rate of approximately 0.1 s(-1). The random sequential mechanism comprises two routes, one in which the type-2 site is reduced first and subsequently binds nitrite, which is then converted into NO, and another in which the oxidized type-2 site binds nitrite and then accepts an electron to produce NO. At high nitrite concentration, the second route prevails and internal electron transfer is rate-limiting. The midpoint potentials of both sites could be established under catalytic conditions. Binding of nitrite to the type-2 site does not affect the midpoint potential of the type-1 site, thereby excluding cooperativity between the two sites.

show abstract

Section: Discussionmentioning

confidence: 60%

Protein Film Voltammetry of Copper-Containing Nitrite Reductase Reveals Reversible Inactivation

et al. 2007

Self Cite

View full text Add to dashboard Cite

show abstract

“…115,122–124 In this work, we focus on the degree to which DFTB3/MM is able to describe the structural and energetic properties of plastocyanin in different copper oxidation states. We leave a more systematic dissection of residual contributions, comparison to related blue copper proteins (e.g., rusticyanin) and the effect of pH 125,126 to future studies.…”

Section: Resultsmentioning

confidence: 99%

Copper Oxidation/Reduction in Water and Protein: Studies with DFTB3/MM and VALBOND Molecular Dynamics Simulations

et al. 2015

View full text Add to dashboard Cite

We apply two recently developed computational methods, DFTB3 and VALBOND, to study copper oxidation/reduction processes in solution and protein. The properties of interest include the coordination structure of copper in different oxidation states in water or in a protein (plastocyanin) active site, the reduction potential of the copper ion in different environments, and the environmental response to copper oxidation. The DFTB3/MM and VALBOND simulation results are compared to DFT/MM simulations and experimental results whenever possible. For a solvated copper ion, DFTB3/MM results are generally close to B3LYP/MM with a medium basis, including both solvation structure and reduction potential for Cu(II); for Cu(I), however, DFTB3/MM finds a two-water coordination, similar to previous Born-Oppenheimer molecular dynamics simulations using BLYP and HSE, while B3LYP/MM leads to a tetrahedron coordination. For a tetra-ammonia copper complex in solution, VALBOND and DFTB3/MM are consistent in terms of both structural and dynamical properties of solvent near copper for both oxidation states. For copper reduction in plastocyanin, DFTB3/MM simulations capture the key properties of the active site, and the computed reduction potential and reorganization energy are in fair agreement with experiment, especially when periodic boundary condition is used. Overall, the study supports the value of VALBOND and DFTB3(/MM) to the analysis of fundamental copper redox chemistry in water and protein, and the results also help highlight areas where further improvements in these methods are desirable.

show abstract

“…The latter is related to the fact that a change of a net charge on the protein surface induces a more or less localized modification of the H-bonding network in the hydration shell of the protein. A number of models for the hydration of nonpolar solutes and biopolymers recognize that these solvent reorganization effects induce largely compensating enthalpy and entropy changes [2,15, 41,42]. In particular, according to Grunwald [4, 9] the free energy change for a process of protein reduction in solution is given by:

Δ {G °}_{obs}^{red} = Δ {G °}_{int} + Δ {G °}_{env}

The intrinsic (nominal) term (Δ G ° int ) represents the free energy change for reduction of the solvated oxidized protein and consists of the term for reduction in the gas phase plus the difference in free energy of solvation between the reduced and oxidized protein.…”

Section: Discussionmentioning

confidence: 99%

Control of reduction thermodynamics in [2Fe–2S] ferredoxins

Bellei

Battistuzzi

et al. 2010

Journal of Inorganic Biochemistry

Self Cite

View full text Add to dashboard Cite

The reaction thermodynamics for the one-electron reduction of the [2Fe-2S] cluster of both human ferredoxin and various surface point mutants, in which each of the negatively charged residues Asp72, Glu73, Asp76, and Asp79 were converted to Ala, have been determined by variable temperature spectroelectrochemical measurements. The above are conserved residues that have been implicated in interactions between the vertebrate-type ferredoxins and their redox partners. In all cases, and similar to other 2Fe-ferredoxins, the reduction potentials are negative as a result of both an enthalpic and entropic stabilization of the oxidized state. Although all Hs Fd mutants, with the exception of Asp72Ala, show slightly higher E°’ values than that of wild type Hs Fd, according to expectations for a purely electrostatic model, they exhibit changes in the ΔH°’rc values that are electrostatically counter-intuitive. The observation of enthalpy-entropy compensation within the protein series indicates that the mutation-induced changes in ΔH°'rc and ΔS°'rc are dominated by reduction-induced solvent reorganization effects. Protein-based entropic effects are likely to be responsible for the low E°’ value of D72A.

show abstract

The effect of pH and ligand exchange on the redox properties of blue copper proteins

Cited by 42 publications

References 54 publications

Protein Film Voltammetry of Copper-Containing Nitrite Reductase Reveals Reversible Inactivation

Protein Film Voltammetry of Copper-Containing Nitrite Reductase Reveals Reversible Inactivation

Copper Oxidation/Reduction in Water and Protein: Studies with DFTB3/MM and VALBOND Molecular Dynamics Simulations

Control of reduction thermodynamics in [2Fe–2S] ferredoxins

Contact Info

Product

Resources

About