Voltammetric response of horse heart cytochrome c at a gold electrode in the presence of sulfur bridged bipyridines

Taniguchi, Ikuo; Toyosawa, Kenji; Yamaguchi, Hiroko; Yasukouchi, Kazuo

doi:10.1016/0368-1874(82)85313-6

Cited by 205 publications

(71 citation statements)

References 18 publications

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“…In addition, recently we found that direct electrochemistry of the weakly acidic blue copper proteins, azurin and umecyanin can also be performed at a bare glassy carbon electrode (unpublished data). Glassy carbon and gold electrodes modified with bis(4-pyridyl) disulfide [56] gave well-defined cyclic voltammograms, and sweep rate dependencies (data now shown) were similar to those obtained using the bare glassy carbon electrode (Fig. 2).…”

Section: Discussionsupporting

confidence: 73%

Electron transfer reaction of stellacyanin at a bare glassy carbon electrode

Ikeda

Sakurai

1994

European Journal of Biochemistry

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Direct (unmediated) electrochemistry of Rhus verniciferu stellacyanin at a glassy carbon electrode has been briefly investigated in phosphate buffer. The voltammetry was practically independent of the buffer concentration, suggesting that the interaction between stellacyanin and the glassy carbon electrode is mainly realized through the hydrophobic interaction. The quasi-reversible process was found to be diffusion controlled at a sweep rate < 80 mVs-I. From stellacyanin concentration dependence, a transformation from linear diffusion to radial diffusion was observed. Twostep voltammetry was affected by translocations of the active site (rotation of the protein molecule on the electrode surface and diffusion). Activation energies for reduction and oxidation processes were determined to be 24kJmol-' and 54k.Tmol-l, respectively, by the stationary method, and 15 k.Tmol-' and 66 Hmol-I, respectively, by cyclic voltammetry. The considerable difference in the activation energies is supposedly due to the reduction and oxidation which are performed utilizing different electron-transfer pathways or because only one electron-transfer pathway (probably through His92) is significantly changed during the reorganization between the oxidized and reduced forms. The fact that the diffusion constant estimated from one-step voltammetry (Dox= 4.2 X10-9 cm2 s-I for 484 pM stellacyanin) is much smaller than that determined from cyclic voltammetry (7.5X10-7 cm2 s-I) derives from the fact that motions of the stellacyanin molecule (rotation leading to translocation of the active site and diffusion) are not fast enough to allow data from potential step voltammetry to be treated as the reversible process, but are fast enough to allow data from cyclic voltammetry to be treated as a diffusion-controlled process.The electron-transfer reaction has received special attention for more than fifty years, since it is involved in important biological processes such as photosynthesis and respiration [l-41. Many of the studies have focused on revealing how the electron-transfer chains are constituted by the relevant proteins, how the redox couple recognize each other, and how the intermolecular and intramolecular electron transfers take place.The rate of the biological electron-transfer processes depends on an interplay of several factors such as the distance between the donor and acceptor, their orientation with respect to each other, the nature of the intervening medium and the groups involved in the transfer pathway, the thermodynamic driving force, and atomic motions coupled with electron transfer [ 5 ] .Together with cytochromes and iron-sulfur proteins, blue copper proteins also play a role in biological electron transfers [6, 71. This type of metalloprotein contains only oneCorrespondence to

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Section: Discussionsupporting

confidence: 73%

Electron transfer reaction of stellacyanin at a bare glassy carbon electrode

Ikeda

Sakurai

1994

European Journal of Biochemistry

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“…35 The k 0 value calculated for the Cyt c on Hpyt SAM was 2.29 10 -3 cm s -1 and resulted to be lower than those calculated for the SAMs formed with pyS (6.0 10 -3 cm s -1 ) and [Ru(CN) 5 (pyS)] 3-complex (8.0 10 -3 cm s -1 ) on gold. 24,36 Taking into account the similarity between the charge density on the terminal group of these modifiers and on the nitrogen terminal atom of the Hpyt SAM, the results can be explained by differences in the configuration of the adsorbates on surface. Previously reported results 19,24 indicate a trans conformation of pyS and [Ru(CN) 5 (pyS)] 3-adsorbates on gold surface.…”

Section: Electroactivity Of the Hpyt Sammentioning

confidence: 99%

5-(4-pyridinyl)-1,3,4-oxadiazole-2-thiol on gold: SAM Formation and electroactivity

Paulo

Silva

Pinheiro

et al. 2008

J. Braz. Chem. Soc.

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O composto 5-(4-pyridinyl)-1,3,4-oxadiazole-2-thiol (Hpyt) adsorve espontaneamente sobre ouro formando SAMs ("Self-Assembled Monolayers") que, de acordo com os resultados eletroquímicos e de STM ("Scanning Tunneling Microscopy"), contêm poros através dos quais as moléculas dos complexos [Fe(CN) 6 ] 4-, a dependência da corrente faradáica com o pH da solução eletrolítica permitiu o cálculo do pKa da molécula de Hpyt adsorvida sobre ouro (4,2). Os parâmetros termodinâmicos, H ads and G ads , para o processo de adsorção desta molécula foram estimados em -20,01 e -39,39 kJ mol -1 , respectivamente, utilizando-se o modelo de Langmuir. O processo redox da metaloproteína citocromo c foi estudado utilizando-se a SAM de Hpyt. A constante de velocidade heterogênea de transferência de elétrons foi calculada em 2,29 10 -3 cm s -1 .5-(4-pyridinyl)-1,3,4-oxadiazole-2-thiol (Hpyt) spontaneously adsorbs on gold forming SAMs (self-assembled monolayers) that, based on STM (Scanning Tunneling Microscopy) and electrochemical data, contain pinholes through which [Fe(CN) 6 ] 4-and [Ru(NH 3 ) 6 ] 3+ probe molecules access the underlying gold electrode. For the former molecule, the dependence of the faradaic current on the electrolyte solution pH value allowed the evaluation of the surface pKa as 4.2. The thermodynamic parameters H ads and G ads for the Hpyt adsorption process could be described by the Langmuir model and were calculated as -20.01 and -39.39 kJ mol -1 , respectively. Electrodic redox reaction of cytochrome c metalloprotein was accessed by using the Hpyt SAM with a heterogeneous electron transfer rate constant of 2.29 10 -3 cm s -1 .

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“…In fact, the direct electrochemistry of cytochrome c on electrodes is the most widely investigated among all redox proteins. Since the ®rst quasi-reversible electrochemistry of cytochrome c at a gold electrode with a promoter 4,4 H -bipyridyl was reported in 1977 [3], many other compounds have been used to promote the electron transfer of cytochrome c on electrodes [4±9]. More recently, carboxylic acid-terminated alkanethiols have been used as electrode modi®ers and thus cytochrome c was electrostatically adsorbed onto the modi®ed layer in low ionic strength buffer.…”

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confidence: 99%

Cytochrome c/Clay-Modified Electrode

et al. 1999

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The direct electrochemical behavior of a small metalloprotein cytochrome c incorporated in a montmorillonite-modi®ed membrane is described. The interaction of cytochrome c with the clay colloidal particles was investigated using electrochemical and spectrophotometric methods. The incorporated cytochrome c in the clay-modi®ed membrane displayed a diffusion-controlled electrode process and still maintained its biological activity.

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Voltammetric response of horse heart cytochrome c at a gold electrode in the presence of sulfur bridged bipyridines

Cited by 205 publications

References 18 publications

Electron transfer reaction of stellacyanin at a bare glassy carbon electrode

Electron transfer reaction of stellacyanin at a bare glassy carbon electrode

5-(4-pyridinyl)-1,3,4-oxadiazole-2-thiol on gold: SAM Formation and electroactivity

Cytochrome c/Clay-Modified Electrode

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