Theoretical study of a surface electrode reaction preceded by a homogeneous chemical reaction under conditions of square-wave voltammetry

Gulaboski, Rubin; Mirčeski, Valentin; Lovrić, Milivoj; Bogeski, Ivan

doi:10.1016/j.elecom.2005.03.009

Cited by 35 publications

(56 citation statements)

References 40 publications

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“…This effect always exists in potential regions after the faradaic process occurs [14][15][16][17][21][22][23][24][25]32]. This phenomenon is typical for all catalytic mechanisms (EC′, or EEC′), while it does not exist by EC or CE systems [14,17,[22][23][24]33,[40][41][42]. When both electrochemical steps of the protein-film EEC′ mechanism are separated for 100 mV or more at the potential scale, then the kinetic and thermodynamic parameters of both redox steps, as well the rate constant of the catalytic reaction (i.e.…”

Section: Discussionmentioning

confidence: 99%

“…The redox transformations of the aforementioned proteins can only be described by theoretical models considering successive two-step electron transfer. In the last few years, we started theoretical considerations of various redox mechanisms relevant to protein-film voltammetry, and we published scores of theoretical and experimental works in the past decade [17,21,22,25,[27][28][29][30][31][32][33][34]. In this paper we consider the surface catalytic mechanism that follows the two-step surface EE (electron-electron) redox reaction, which can be described by the following reaction scheme: The common designation of this complex protein-film redox mechanism in the electrochemical terminology is a surface EEC′, or surface EECat [13,14].…”

Section: Introductionmentioning

confidence: 99%

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Catalytic mechanism in successive two-step protein-film voltammetry—Theoretical study in square-wave voltammetry

Gulaboski

Mihajlov

2011

Biophysical Chemistry

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Protein-film voltammetry is established as an effective tool that provides insight to the redox features of various lipophilic proteins by using a simple methodology. Although the protein-film experimental set up is relatively simple, the redox mechanisms of many proteins are quite complicated, and very often they cannot be resolved without having support from adequate mathematical models. In this work we continue our contribution to modeling relevant redox mechanisms in protein-film voltammetry. We present results from the theoretical simulations of catalytic mechanism at the two-step successive surface redox reaction under conditions of square-wave voltammetry. This mechanism is assigned as a surface EEC′, and it can be presented by the following simplified scheme: A(ads) + ne− ⇄ B(ads) + ne− ⇄ C(ads) + Substrate → kcat B(ads). Our attention is focused on several phenomena of this complex protein-film mechanism, while we give set of qualitative criteria to distinguish this mechanism from similar ones studied under voltammetric conditions. Moreover, we also provide hints to use methodologies for the determination of thermodynamic and kinetic parameters relevant to the protein-film EEC′ mechanism. The considered protein-film EEC′ mechanism is applicable to all lipophilic redox proteins that undergo electrochemical transformations in more than one successive electron steps. Such examples exist by proteins containing quinone moiety and some polyvalent ions of transition metals as redox active sites.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Catalytic mechanism in successive two-step protein-film voltammetry—Theoretical study in square-wave voltammetry

Gulaboski

Mihajlov

2011

Biophysical Chemistry

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“…As well known, the surface confined electrode processes are important for understanding the electrochemistry of conducting polymers, self-assembled monolayers, hydrophobic proteins, redox active drugs and coenzymes etc. Hence, novel experimental strategies for kinetic characterization of surface confined processes [48][49][50] at a constant scan rate are of obvious importance, in particular when complex electrode mechanisms are considered, the voltammetric response of which depends on numerous frequency-related parameters. Finally, determination of the rate of the redox transformations of vitamins K2 and B12 has particular biochemical significance.…”

Section: Introductionmentioning

confidence: 99%

Measuring the Electrode Kinetics of Surface Confined Electrode Reactions at a Constant Scan Rate

2014

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The kinetics of surface confined electrode reactions of alizarin, vitamin B12, and vitamin K2 is measured with square‐wave voltammetry over a wide pH interval, by applying the recent methodology for kinetic analysis at a constant scan rate [V. Mirceski, D. Guziejewski, K. Lisichkov, Electrochim. Acta 2013, 114, 667–673]. The reliability and the simplicity of the recent methodology is confirmed. The methodology requires analysis of the peak potential separation of the forward and backward component of the response as a function of the pulse height (SW amplitude), for a given frequency (i.e. constant scan rate) of the potential modulation.

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“…Noteworthy, hexacoordination of the heme iron favors reduction kinetics comparing to pentacoordinated analogues (50). the kinetics of O 2 dissociation are relatively slow compared with the time scale of the performed electrochemical measurements (56). However, faster scan rates can be applied if necessary.…”

Section: Resultsmentioning

confidence: 99%

Electrochemical Evidence for Neuroglobin Activity on NO at Physiological Concentrations

Trashin¹,

Jong²,

Luyckx

et al. 2016

Journal of Biological Chemistry

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The true function of neuroglobin (Ngb) and, particularly, human Ngb (NGB) has been under debate since its discovery 15 years ago. It has been expected to play a role in oxygen binding/ supply, but a variety of other functions have been put forward, including NO dioxygenase activity. However, in vitro studies that could unravel these potential roles have been hampered by the lack of an Ngb-specific reductase. In this work, we used electrochemical measurements to investigate the role of an intermittent internal disulfide bridge in determining NO oxidation kinetics at physiological NO concentrations. The use of a polarized electrode to efficiently interconvert the ferric (Fe 3؉ ) and ferrous (Fe 2؉ ) forms of an immobilized NGB showed that the disulfide bridge both defines the kinetics of NO dioxygenase activity and regulates appearance of the free ferrous deoxy-NGB, which is the redox active form of the protein in contrast to oxy-NGB. Our studies further identified a role for the distal histidine, interacting with the hexacoordinated iron atom of the heme, in oxidation kinetics. These findings may be relevant in vivo, for example, in blocking apoptosis by reduction of ferric cytochrome c, and gentle tuning of NO concentration in the tissues. Neuroglobin (Ngb)2 is the vertebrate globin that has been hypothesized to be involved in, e.g. O 2 binding/supply, the metabolism of reactive nitrogen and oxygen species, apoptosis through different pathways, intracellular signaling, and cell protection during hypoxia and ischemia (1-6). Besides the central and peripheral nervous system and retina, Ngb is also expressed in endocrine tissues, hematopoietic stem cells, the gastrointestinal tract, and cancer cells (7,8). Although the first publication on the subject was in 2000, the in vivo role of Ngb is still uncertain. Studies on Ngb knock-out mice and regional gene expression did not clarify it further (3, 9 -13), but most of the reports in the topic supported its neuroprotective function at least under conditions of neuroglobin overexpression (11,14,15). Some histological data additionally indicated that Ngb can be involved in regulation of the circadian rhythm (sleep-wake cycle) (12, 16) and protection of neurons from neurodegenerative disorders, such as Alzheimers disease (17)(18)(19). Obviously, further in vivo and in vitro studies of Ngb are necessary to clarify its molecular mechanisms of action.As other globins, e.g. myoglobin and hemoglobin, Ngb displays the three-over-three ␣-helical sandwich structure. However, Ngb structurally differs somewhat from myoglobin and hemoglobin, suggesting a different functional destination for Ngb compared with the classic globins (20). Both its weak O 2 binding affinity under physiological conditions (21) and its hexacoordinated structure of the iron atom of the heme leading to a possible intrinsic binding competition with external gaseous ligands such as O 2 , CO, and NO, support the hypothesis that Ngb is not constructed to transport or store O 2 (22). The unclear mechanism of actio...

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Theoretical study of a surface electrode reaction preceded by a homogeneous chemical reaction under conditions of square-wave voltammetry

Cited by 35 publications

References 40 publications

Catalytic mechanism in successive two-step protein-film voltammetry—Theoretical study in square-wave voltammetry

Catalytic mechanism in successive two-step protein-film voltammetry—Theoretical study in square-wave voltammetry

Measuring the Electrode Kinetics of Surface Confined Electrode Reactions at a Constant Scan Rate

Electrochemical Evidence for Neuroglobin Activity on NO at Physiological Concentrations

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