Kinetics of the reduction of cytochrome c by [FeII(edta)(H2O)]2−: outer-sphere vs. inner-sphere electron transfer mechanisms

Macyk, Joanna; Eldik, Rudi van

doi:10.1039/b301424j

Cited by 13 publications

(7 citation statements)

References 49 publications

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“…The same changes were obtained for Cyt c treated with dithionite (data not shown) and are typical for reduced form of this protein. 21 For parallel samples, incubated in darkness, there were only weak changes, although of the same type, suggesting that even non-illuminated QDs had some surface electrons that can be transferred to the heme moieties. Reduction of Cyt c was stableno signicant changes of spectrum were observed for at least 1 h of following incubation of illuminated samples when stored in darkness or weak light.…”

Section: Spectrophotometric Characterization Of Ferredoxin and Cytoch...mentioning

confidence: 95%

Photoreduction of natural redox proteins by CdTe quantum dots is size-tunable and conjugation-independent

2015

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Colloidal CdTe quantum dots (QD) were able to reduce both heme and iron-sulfur cluster containing proteins. Reduction was depended on quantum dots size. CdTe nanocrystals emitting light with maximum at 550 nm (QD-550, r $ 1.5 nm) reduced both ferredoxin (Fd) and cytochrome c (Cyt c). The process was followed by UV/Vis absorption spectroscopy and steady state fluorescence spectroscopy. For CdTe emitting longer wavelength (QD-610 and QD-670) reduction of Fd was less efficient. QD emitting light with maximum at 750 nm (QD-750, r $ 3.3 nm) reduced only Cyt c. Reduction of proteins by QDs was photo-dependent and did not demand oxygen presence. As shown by gel filtration and fluorescence correlation spectroscopy, Fd formed complexes with QD while Cyt c did not bound steadily. The stable complex was not necessary for photoreduction, although might influence its kinetics.Time-resolved fluorescence studies showed than electron transfer rate depends on QD size and also is higher for QD-Cyt c when compared to QD-Fd. The mechanism of process was additionally explored by detailed analysis of QD-protein complex formation and by measurements of cyclic voltamperometry and zeta potential. These results open new possibilities in controlling of natural redox processes. † Electronic supplementary information (ESI) available: Fluorescence analysis of fraction from gel ltration, example of FCS curves, example of uorescence decay curves. See

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Section: Spectrophotometric Characterization Of Ferredoxin and Cytoch...mentioning

confidence: 95%

Photoreduction of natural redox proteins by CdTe quantum dots is size-tunable and conjugation-independent

2015

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“…The positions of the peaks in the spectrum for the reduced form are in good agreement with previous reports, indicating that the protein is completely reduced. [8,40] The extinction coefficient of reduced cytochrome c at 400 nm was deduced to be e R = 3.79 (AE 0.06) 10 4 dm 3 mol À1 cm…”

Section: Uv/vis Spectroscopymentioning

confidence: 99%

“…[6] Traditionally, obtaining the kinetics of ET between proteins and redox mediators or other proteins was achieved in homogeneous solution using stopped flow apparatus and monitoring the change in the redox state of the protein by absorption spectroscopy. [7][8][9][10][11] However, since the first successful demonstrations of cyclic voltammetry of horse heart cytochrome c by Eddowes and Hill [12] and Yeh and Kuwana [13] independently in 1977, the area of the direct and mediated electrochemistry of both ET proteins and complex enzymes has flourished. [2,14] Protein film voltammetry (PFV) [15] is widely accepted as a powerful tool for understanding ET between proteins and electrodes for the fabrication of devices such as biosensors, [2,16] in bioelectronics and biofuel cells, [8,9] and as a model approach for comprehending ET between redox proteins in vivo.…”

Section: Introductionmentioning

confidence: 99%

“…[7][8][9][10][11] However, since the first successful demonstrations of cyclic voltammetry of horse heart cytochrome c by Eddowes and Hill [12] and Yeh and Kuwana [13] independently in 1977, the area of the direct and mediated electrochemistry of both ET proteins and complex enzymes has flourished. [2,14] Protein film voltammetry (PFV) [15] is widely accepted as a powerful tool for understanding ET between proteins and electrodes for the fabrication of devices such as biosensors, [2,16] in bioelectronics and biofuel cells, [8,9] and as a model approach for comprehending ET between redox proteins in vivo. [17] In PFV, a potential applied at an electrode drives electrons in and out of the active sites of an electroactive protein film immobilized on the electrode, allowing the evaluation of the formal potentials and the rates of ET and other kinetic and thermodynamic parameters.…”

Section: Introductionmentioning

confidence: 99%

“…[8,11,48] The comparatively low ET rate constant deduced from our measurements is perhaps not unexpected, since immobilization of cytochrome c on the silica surface may result in an unfavourable orientation of the heme group due to electrostatic interactions between the positively charged lysine residues surrounding the active site [49] and the negatively charged silica surface. Furthermore, the relatively high surface coverages of cytochrome c used in this study mean that the ET rate constant could be retarded due to molecular crowding effects.…”

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confidence: 98%

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Probing Redox Reactions of Immobilized Cytochrome c Using Evanescent Wave Cavity Ring‐Down Spectroscopy in a Thin‐Layer Electrochemical Cell

et al. 2010

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We report the use of evanescent wave cavity ring-down spectroscopy (EW-CRDS) to monitor the reduction by ethylenediaminetetraacetic acid iron(II) complex, [FeEDTA](2-), of an adsorbed layer of oxidized cytochrome c immobilized on fused silica. The adsorption of cytochrome c at the silica-water interface was also probed using EW-CRDS and found to be in qualitative agreement with previous studies. The reduction of the adsorbed cytochrome c was achieved by using a strategically positioned electrode to electrogenerate FeEDTA(2-), which diffused to the silica surface and reduced the cytochrome c. The difference in the absorption spectra of the reduced and oxidized forms of cytochrome c at 400 nm allowed the direct monitoring of the electron transfer in real time. Using finite-element modelling, the rate constant of electron transfer (ET) between FeEDTA(2-) and cytochrome c was found to be 4.3(± 0.6) × 10(-9) cm s(-1) equivalent to 2.7(± 0.4) M(-1) s(-1). The latter value is considerably lower than previously reported ET rate constants between cytochrome c and FeEDTA(2-) in solution, which can be attributed to the confinement of the immobilized cytochrome c on the surface and possible effects from molecular crowding. This study highlights the importance of new methods which can be used to study ET at interfaces and opens up the possibility of studying ET to proteins in biologically relevant environments using EW-CRDS.

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High Pressure Chemistry

Hubbard

Eldik

2005

Kirk-Othmer Encyclopedia of Chemical Technology

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The technology associated with application of hydrostatic pressure in chemistry is presented. Apparatus and equipment range from a straightforward autoclave‐type arrangement to more sophisticated techniques of subjecting materials or chemical reactions in solution to pressure, and monitoring events caused by pressure application while the system is under pressure (ie, in situ ). Spectroscopic detection is the principal monitoring technique in in situ methods. The wide span of time ranges of changes taking place during a pressure cycle requires different types of technologies and these are described. The type of system under investigation directs the choice of method and the range of pressure applied. For synthetic and preparative solution chemistry, pressures up to a few thousand megapascals (MPa) have been used. For processing of materials to bring about a change in properties, pressures up to 600 MPa are usually adequate, whereas for most mechanistic studies pressures > 200 MPa are rarely used (1 atm = 1.01325 × 10 5 Pa; 1 Pa = 1 N/m 2 ). Examples of systems studied from organic chemistry, inorganic chemistry, bioinorganic chemistry, and colloid chemistry are provided. These clearly illustrate the value of applying hydrostatic pressure and demonstrate insight into understanding physicochemical and chemical changes that occur. Such insight is not normally achievable by other experimental approaches and highlights the unique value and success of high pressure technology in chemistry.

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Kinetics of the reduction of cytochrome c by [Fe^II(edta)(H₂O)]²⁻: outer-sphere vs. inner-sphere electron transfer mechanisms

Cited by 13 publications

References 49 publications

Photoreduction of natural redox proteins by CdTe quantum dots is size-tunable and conjugation-independent

Photoreduction of natural redox proteins by CdTe quantum dots is size-tunable and conjugation-independent

Probing Redox Reactions of Immobilized Cytochrome c Using Evanescent Wave Cavity Ring‐Down Spectroscopy in a Thin‐Layer Electrochemical Cell

High Pressure Chemistry

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