Function of C-terminal hydrophobic region in fructose dehydrogenase

Sugimoto, Yu; Kawai, Shigeyuki; Kitazumi, Yuki; Shirai, Osamu; Kano, Kenji

doi:10.1016/j.electacta.2015.07.142

Cited by 9 publications

(6 citation statements)

References 28 publications

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“…Finally, the stability and lifetime of the FDH/2-ANT/SWCNT/GCE has been evaluated by monitoring the amperometric signal decrease over 60 days (Figure B), showing 90% retainment of the initial signal. which is ascribable to the correct orientation of FDH onto the electrode surface and the strength of the π–π interaction between the anthracenyl groups and the aromatic groups in the side chain of the amino acids present in the hydrophobic region, as was previously also shown for laccase …”

Section: Results and Discussionsupporting

confidence: 67%

“…In the overall electrocatalytic wave, it is possible to clearly see that it is divided into three parts: (i) the first sigmoidal catalytic wave starting in correspondence to heme c 1 of FDH (−0.1 V to +0.050 V), (ii) the second sigmoidal catalytic wave starting in correspondence to heme c 2 of FDH not visible in the non-turnover signal (+0.050 to +0.250 V), and (iii) the mass-transfer-limited current due to the limited diffusion of the substrate to the electrode (+0.250 to +0.550 V). − This result could be explained by the enhanced roughness of the electrode surface improving the enzyme loading and the correct orientation of FDH due to the interaction between the anthracenyl group and the hydrophobic part of subunit II. In particular, the interaction occurs between the aromatic rings of the anthracenyl group and the aromatic rings available on the side chain of the amino acids present in the hydrophobic portion of subunit II (π–π interaction) …”

Section: Results and Discussionmentioning

confidence: 99%

“…In particular, the interaction occurs between the aromatic rings of the anthracenyl group and the aromatic rings available on the side chain of the amino acids present in the hydrophobic portion of subunit II (π−π interaction). 86 The effect of the scan rate of the CVs was investigated for the non-turnover DET reaction of the immobilized FDH at the SWCNT/GCE and 2-ANT/SWCNT/GCE. The CVs at different scan rates for these electrodes are reported in parts A and B of Figure 4, respectively.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Enhanced Direct Electron Transfer of Fructose Dehydrogenase Rationally Immobilized on a 2-Aminoanthracene Diazonium Cation Grafted Single-Walled Carbon Nanotube Based Electrode

et al. 2018

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In this paper, an efficient direct electron transfer (DET) reaction was achieved between fructose dehydrogenase (FDH) and a glassy-carbon electrode (GCE) upon which anthracene-modified single-walled carbon nanotubes were deposited. The SWCNTs were activated in situ with a diazonium salt synthesized through the reaction of 2-aminoanthracene with NaNO 2 in acidic media (0.5 M HCl) for 5 min at 0 °C. After the in situ reaction, the 2-aminoanthracene diazonium salt was electrodeposited by running cyclic voltammograms from +1000 to −1000 mV. The anthracene-SWCNT-modified GCE was further incubated in an FDH solution, allowing enzyme adsorption. Cyclic voltammograms of the FDH-modified electrode revealed two couples of redox waves possibly ascribed to the heme c 1 and heme c 3 of the cytochrome domain. In the presence of 10 mM fructose two catalytic waves could clearly be seen and were correlated with two heme cs (heme c 1 and c 2 ), with a maximum current density of 485 ± 21 μA cm −2 at 0.4 V at a sweep rate of 10 mV s −1 . In contrast, for the plain SWCNT-modified GCE only one catalytic wave and one couple of redox waves were observed. Adsorbing FDH directly onto a GCE showed no nonturnover electrochemistry of FDH, and in the presence of fructose only a slight catalytic effect could be seen. These differences can be explained by considering the hydrophobic pocket close to heme c 1 , heme c 2 , and heme c 3 of the cytochrome domain at which the anthracenyl aromatic structure could interact through π−π interactions with the aromatic side chains of the amino acids present in the hydrophobic pocket of FDH.

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Section: Results and Discussionsupporting

confidence: 67%

Section: Results and Discussionmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Enhanced Direct Electron Transfer of Fructose Dehydrogenase Rationally Immobilized on a 2-Aminoanthracene Diazonium Cation Grafted Single-Walled Carbon Nanotube Based Electrode

et al. 2018

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“…Among the flavocytochrome oxidoreductases, the DET mechanism for membrane bound FDH has not yet been elucidated [ 45 ] and therefore FDH has attracted a growing interest also regarding all factors that can influence the DET reaction (e.g., pH, cations, ionic strength, etc.) [ 46 – 48 ].…”

Section: Introductionmentioning

confidence: 99%

The influence of pH and divalent/monovalent cations on the internal electron transfer (IET), enzymatic activity, and structure of fructose dehydrogenase

et al. 2018

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We report on the influence of pH and monovalent/divalent cations on the catalytic current response, internal electron transfer (IET), and structure of fructose dehydrogenase (FDH) by using amperometry, spectrophotometry, and circular dichroism (CD). Amperometric measurements were performed on graphite electrodes, onto which FDH was adsorbed and the effect on the response current to fructose was investigated when varying the pH and the concentrations of divalent/monovalent cations in the contacting buffer. In the presence of 10 mM CaCl2, a current increase of up to ≈ 240% was observed, probably due to an intra-complexation reaction between Ca2+ and the aspartate/glutamate residues found at the interface between the dehydrogenase domain and the cytochrome domain of FDH. Contrary to CaCl2, addition of MgCl2 did not show any particular influence, whereas addition of monovalent cations (Na+ or K+) led to a slight linear increase in the maximum response current. To complement the amperometric investigations, spectrophotometric assays were carried out under homogeneous conditions in the presence of a 1-electron non-proton-acceptor, cytochrome c, or a 2-electron-proton acceptor, 2,6-dichloroindophenol (DCIP), respectively. In the case of cytochrome c, it was possible to observe a remarkable increase in the absorbance up to 200% when 10 mM CaCl2 was added. However, by further increasing the concentration of CaCl2 up to 50 mM and 100 mM, a decrease in the absorbance with a slight inhibition effect was observed for the highest CaCl2 concentration. Addition of MgCl2 or of the monovalent cations shows, surprisingly, no effect on the electron transfer to the electron acceptor. Contrary to the case of cytochrome c, with DCIP none of the cations tested seem to affect the rate of catalysis. In order to correlate the results obtained by amperometric and spectrophotometric measurements, CD experiments have been performed showing a great structural change of FDH when increasing the concentration CaCl2 up to 50 mM, at which the enzyme molecules start to agglomerate, hindering the substrate access to the active site probably due to a chelation reaction occurring at the enzyme surface with the glutamate/aspartate residues. Graphical AbstractFructose dehydrogenase (FDH) consists of three subunits, but only two are involved in the electron transfer process: (I) 2e−/2H+ fructose oxidation, (II) internal electron transfer (IET), (III) direct electron transfer (DET) through 2 heme c; FDH activity either in solution or when immobilized onto an electrode surface is enhanced about 2.5-fold by adding 10 mM CaCl2 to the buffer solution, whereas MgCl2 had an “inhibition” effect. Moreover, the additions of KCl or NaCl led to a slight current increase Electronic supplementary materialThe online version of this article (10.1007/s00216-018-0991-0) contains supplementary material, which is available to authorized users.

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“…KCl) was suggested as a bridge between FAD and heme 2c in the IET process (Figure 4) [30]. In addition, the catalytic current density of FDH was dramatically increased by deleting the amino acid residues on the N-or C-terminus of subunit II [30,105,106]. The deletion not only promotes enzyme loading but also provides more opportunities for favorable orientations on the electrode surface.…”

Section: Fructose Dehydrogenasementioning

confidence: 99%

Direct Electrochemical Enzyme Electron Transfer on Electrodes Modified by Self-Assembled Molecular Monolayers

et al. 2020

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Self-assembled molecular monolayers (SAMs) have long been recognized as crucial “bridges” between redox enzymes and solid electrode surfaces, on which the enzymes undergo direct electron transfer (DET)—for example, in enzymatic biofuel cells (EBFCs) and biosensors. SAMs possess a wide range of terminal groups that enable productive enzyme adsorption and fine-tuning in favorable orientations on the electrode. The tunneling distance and SAM chain length, and the contacting terminal SAM groups, are the most significant controlling factors in DET-type bioelectrocatalysis. In particular, SAM-modified nanostructured electrode materials have recently been extensively explored to improve the catalytic activity and stability of redox proteins immobilized on electrochemical surfaces. In this report, we present an overview of recent investigations of electrochemical enzyme DET processes on SAMs with a focus on single-crystal and nanoporous gold electrodes. Specifically, we consider the preparation and characterization methods of SAMs, as well as SAM applications in promoting interfacial electrochemical electron transfer of redox proteins and enzymes. The strategic selection of SAMs to accord with the properties of the core redox protein/enzymes is also highlighted.

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Function of C-terminal hydrophobic region in fructose dehydrogenase

Cited by 9 publications

References 28 publications

Enhanced Direct Electron Transfer of Fructose Dehydrogenase Rationally Immobilized on a 2-Aminoanthracene Diazonium Cation Grafted Single-Walled Carbon Nanotube Based Electrode

Enhanced Direct Electron Transfer of Fructose Dehydrogenase Rationally Immobilized on a 2-Aminoanthracene Diazonium Cation Grafted Single-Walled Carbon Nanotube Based Electrode

The influence of pH and divalent/monovalent cations on the internal electron transfer (IET), enzymatic activity, and structure of fructose dehydrogenase

Direct Electrochemical Enzyme Electron Transfer on Electrodes Modified by Self-Assembled Molecular Monolayers

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