Mediatorless electrocatalytic reduction of hydrogen peroxide at graphite electrodes chemically modified with peroxidases

Csöregi, Elisabeth; Jönsson–Pettersson, G.; Gorton, Lo

doi:10.1016/0168-1656(93)90147-f

Cited by 129 publications

(47 citation statements)

References 24 publications

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“…The different pH optima for the two peroxidases resulted in maximum catalytic activity of RPTP towards ABTS at pH 3.5, and that of HRP at pH 4.8. Comparative studies of peroxidase activities upon addition of organic cosolvent were performed in buffer solutions, pH 6.0, as corresponding to the optimized bioelectrocatalytic activity of peroxidases in DETand in METwith catechol as mediator [33,40,41]. The enzymatic activity of both peroxidases decreased drastically upon addition of ethanol and acetonitrile to the aqueous buffer solution, in agreement with previously reported data [19,39].…”

Section: Enzymatic Activitysupporting

confidence: 74%

Bioelectrocatalysis of Plant Peroxidases Immobilized on Graphite in Aqueous and Mixed Solvent Media

et al. 2005

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The bioelectrocatalytic function of two plant peroxidases, horseradish peroxidase (HRP) and a newly purified royal palm tree-leaf peroxidase (RPTP), was studied on graphite electrodes in aqueous buffer solutions, over the pH range 7.0 -3.0, and in aqueous buffer solutions, at pH 6.0, containing different amounts of a polar organic cosolvent, i.e., ethanol and acetonitrile. The kinetics of direct and of mediated (using catechol as mediator) reduction of H 2 O 2 at the HRP-and RPTP-modified graphite electrodes were analyzed amperometrically at À 50 mV(vs. Ag j AgCl j 0.1 M KCl) in a flow-through wall-jet electrochemical system. Values of the apparent rate constant of the heterogeneous electron transfer between the enzyme and graphite, k s , the rate constant for enzymatic reduction of H 2 O 2 , k 1 , and the rate constant of mediated reduction of H 2 O 2 , k 3, were determined using the modified Koutecky-Levich approach. Analysis of the variation of the rate constants and the response of the peroxidase-modified electrodes to H 2 O 2 with pH and content of the organic cosolvent demonstrated that maximal peroxidase bioelectrocatalytic activity occurred at pH 5.0 -6.0 and at concentrations of ethanol of 10 -20% v/v. At a lower pH, higher concentrations of ethanol, and in aqueous solutions of acetonitrile, the bioelectrocatalytic activity of the peroxidase-modified electrodes drastically decreased. However, contrary to the data for homogeneous catalysis, both peroxidases were bioelectrocatalytically active even in 95% organic co-solvents, thus demonstrating a stabilizing effect of the enzyme immobilization on the bioelectrocatalytic performance of the peroxidases. RPTP immobilized on graphite demonstrated lower overall activity but a higher pH-and organic cosolvent-stability than HRP.

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Section: Enzymatic Activitysupporting

confidence: 74%

Bioelectrocatalysis of Plant Peroxidases Immobilized on Graphite in Aqueous and Mixed Solvent Media

et al. 2005

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“…The electron transfer between HRP and the graphite is apparently direct as first observed by Yaropolov et al [36]. The exact mechanism of electron transfer is, however, still unknown, but it has been observed that carboneous electrode materials rich in oxygen containing surface functionalities efficiently perform the electron mediation [12,[37][38][39][40].…”

Section: Resultsmentioning

confidence: 84%

Pyranose Oxidase Modified Carbon Paste Electrodes for Monosaccharide Determination

et al. 1998

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An amperometric biosensor for the detection of some monosaccharides was developed with co-immobilized pyranose oxidase (purified from the basidiomycete fungus Phanerochaete chrysosporium) and horseradish peroxidase in carbon paste. Due to rather low selectivity of pyranose oxidase, the biosensor could detect both predominating anomers of D-glucose as well as the substrates D-xylose, D-galactose, and d-gluconolactone. The best sensor performance was obtained from a carbon paste with covalently immobilized enzymes together with the additives lactitol and polyethylenimine, resulting in a sensitivity for glucose of 30.2 mA cm ¹2 mM ¹1 . The enzyme modified electrode was investigated in an automated flow injection system at the operating potential of ¹50 mV (vs. Ag/AgCl) with an injection frequency of 40 h ¹1 . The biosensor was also integrated as the detection unit in a liquid chromatographic system for the detection of monosaccharides to show its potential use in real applications.

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“…The electrodes were connected to a three-electrode potentiostat (ZaÈ ta Elektronik, Lund, Sweden) and the current was recorded on a recorder (Kipp and Zonen, The Netherlands). All measurements were performed at an applied potential of )50 mV versus Ag/AgCl (CsoÈ regi et al, 1993;Lindgren et al, 1997;Ruzgas et al, 1995).…”

Section: Horseradish Peroxidase (Hrp)-modi®ed Electrodesmentioning

confidence: 99%

Supercritical fluid extraction of a lignocellulosic hydrolysate of spruce for detoxification and to facilitate analysis of inhibitors

Persson¹,

Larsson²,

Jönsson³

et al. 2002

Biotech & Bioengineering

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This work describes a novel approach to detoxify lignocellulosic hydrolysates and facilitate the analysis of inhibitory compounds, namely supercritical fluid extraction (SFE). The efficiency of the fermentation of lignocellulosic dilute-acid hydrolysates depends upon the composition of the hydrolysate and the organism used. Furthermore, it has been shown that inhibitors in the hydrolysate reduce the fermentation yield. This knowledge has given rise to the need to identify and remove the inhibiting compounds. Sample clean-up or work-up steps, to provide a clean and concentrated sample for the analytical system, facilitate the characterization of inhibitors, or indeed any compound in the hydrolysates. Removal of inhibitors was performed with countercurrent flow supercritical fluid extraction of liquid hydrolysates. Three different groups of inhibitors (furan derivatives, phenolic compounds, and aliphatic acids) and sugars were subsequently analyzed in the hydrolysate, extracted hydrolysate, and extract. The effect of the SFE treatment was examined with respect to fermentability with Saccharomyces cerevisiae. Not only did the extraction provide a clean and concentrated sample (extract) for analysis, but also a hydrolysate with increased fermentability as well as lower concentrations of inhibitors such as phenolics and furan derivatives.

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Mediatorless electrocatalytic reduction of hydrogen peroxide at graphite electrodes chemically modified with peroxidases

Cited by 129 publications

References 24 publications

Bioelectrocatalysis of Plant Peroxidases Immobilized on Graphite in Aqueous and Mixed Solvent Media

Bioelectrocatalysis of Plant Peroxidases Immobilized on Graphite in Aqueous and Mixed Solvent Media

Pyranose Oxidase Modified Carbon Paste Electrodes for Monosaccharide Determination

Supercritical fluid extraction of a lignocellulosic hydrolysate of spruce for detoxification and to facilitate analysis of inhibitors

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