Laccase catalysed oxidation of syringic acid: Calorimetric determination of kinetic parameters

Volkova, Natalia; Ibrahim, Victor; Hatti‐Kaul, Rajni

doi:10.1016/j.enzmictec.2012.01.005

Cited by 16 publications

(12 citation statements)

References 42 publications

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“…There was absence of any redox peaks that are characteristic of redox mediators being regenerated. This might be due to laccase oxidizing syringaldehyde to syringic acid while producing phenoxy radicals and syringic acid further oxidizing to 2,6-dimethoxy-1,4-benzoquinone (DMBQ) [26,27] (Figure 5). Due to the Decolorization using the ABTS-Laccase system was also attempted for comparison but due to heavy interference with the color of ABTS in the presence of laccase (blue), the decolorization could not be studied effectively.…”

Section: Electrochemical Activity Of the Laccase Mediator Systemsmentioning

confidence: 99%

The Role of Natural Laccase Redox Mediators in Simultaneous Dye Decolorization and Power Production in Microbial Fuel Cells

et al. 2018

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Redox mediators could be used to improve the efficiency of microbial fuel cells (MFCs) by enhancing electron transfer rates and decreasing charge transfer resistance at electrodes. However, many artificial redox mediators are expensive and/or toxic. In this study, laccase enzyme was employed as a biocathode of MFCs in the presence of two natural redox mediators (syringaldehyde (Syr) and acetosyringone (As)), and for comparison, a commonly-used artificial mediator 2,2 -azinobis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) was used to investigate their influence on azo dye decolorization and power production. The redox properties of the mediator-laccase systems were studied by cyclic voltammetry. The presence of ABTS and As increased power density from 54.7 ± 3.5 mW m −2 (control) to 77.2 ± 4.2 mW m −2 and 62.5 ± 3.7 mW m −2 respectively. The power decreased to 23.2 ± 2.1 mW m −2 for laccase with Syr. The cathodic decolorization of Acid orange 7 (AO7) by laccase indicated a 12-16% increase in decolorization efficiency with addition of mediators; and the Laccase-Acetosyringone system was the fastest, with 94% of original dye (100 mgL −1 ) decolorized within 24 h. Electrochemical analysis to determine the redox properties of the mediators revealed that syringaldehyde did not produce any redox peaks, inferring that it was oxidized by laccase to other products, making it unavailable as a mediator, while acetosyringone and ABTS revealed two redox couples demonstrating the redox mediator properties of these compounds. Thus, acetosyringone served as an efficient natural redox mediator for laccase, aiding in increasing the rate of dye decolorization and power production in MFCs. Taken together, the results suggest that natural laccase redox mediators could have the potential to improve dye decolorization and power density in microbial fuel cells. Energies 2018, 11, 3455 2 of 12The enzyme is widely utilised in the oxidation of phenolic and non-phenolic substrates such as dyes, pesticides, antibiotics etc.The redox potential of the substrate should be lower than that of laccase for oxidation to be thermodynamically feasible. The redox potential range for fungal laccase is between 0.4-0.8 V vs. standard hydrogen electrode (SHE), which is suitable for oxidation of phenolic substrates; for non-phenolic substrates that have a redox potential of >1.3 V vs. SHE, and cannot be oxidized directly by laccase, a redox mediator is required [5]. A redox mediator is a small molecular weight compound that is oxidized by the enzyme and reduced by the substrate continuously. They act as electron shuttles for large substrates that cannot access the active site of the enzyme, e.g., due to steric hindrance [6]. In laccase mediator systems (LMS), the enzyme oxidizes the mediators to form stable radicals with high redox potential that diffuse away from the enzyme active site and oxidize the substrates and get reduced in the process. In this way, laccase indirectly oxidises substrates that have high redox potentials or large molecular sizes [7] (...

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Section: Electrochemical Activity Of the Laccase Mediator Systemsmentioning

confidence: 99%

The Role of Natural Laccase Redox Mediators in Simultaneous Dye Decolorization and Power Production in Microbial Fuel Cells

et al. 2018

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“…This method was used to determine the kinetic parameters of two laccases from Galerina sp. HC1 and T. versicolor . This technique is suitable especially when other common methods (spectrophotometry, oxygen consumption, etc.)…”

Section: Determination Of Laccase Activitymentioning

confidence: 99%

“…HC1 and T. versicolor. 88 This technique is suitable especially when other common methods (spectrophotometry, oxygen consumption, etc.) have interference risks or are laborious.…”

Section: Isothermal Titration Calorimetrymentioning

confidence: 99%

Insights into laccase producing organisms, fermentation states, purification strategies, and biotechnological applications

Forootanfar

Faramarzi

2015

Biotechnology Progress

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Laccases are phenol oxidases belonging to the superfamily of multicopper oxidases and are found in bacteria, fungi, lichens, higher plants, and insects. Over the past few decades, laccases and laccase mediator systems (LMS) have found uses in a wide range of technological applications such as textile dye decolorization, industrial wastewater detoxification, pulp bleaching, chemical synthesis, and development of miniaturized biosensors. This has encouraged numerous studies to find and purify laccases with exploitable characteristics. The main aim of the present review is to summarize the rich literature data gained in recent years from the studies on laccases, focusing on the organisms that produce them, the methods used for screening, laccase activity assays, purification strategies, and the application of laccases as eco-friendly biocatalysts.

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“…The heat released during an enzymatic process represents a suitable indication of enzymatic activity, which can be used to follow and analyze the kinetics of an enzymatic reaction. Isothermal titration calorimetry (ITC) is known as one of the useful methods to study biological interactions thermodynamics 22. ITC has been successfully applied in the activity analysis of different enzymes both in the free state 22–27 and immobilized on solid supports 21.…”

Section: Introductionmentioning

confidence: 99%

“…Isothermal titration calorimetry (ITC) is known as one of the useful methods to study biological interactions thermodynamics 22. ITC has been successfully applied in the activity analysis of different enzymes both in the free state 22–27 and immobilized on solid supports 21. In the present work, the activity of PUO immobilized on SPCEs was evaluated by ITC.…”

Section: Introductionmentioning

confidence: 99%

Characterization of a Disposable Electrochemical Biosensor Based on Putrescine Oxidase from Micrococcus rubens for the Determination of Putrescine

et al. 2014

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Putrescine oxidase (PUO) from Micrococcus rubens has been characterized, as a biocatalytic component for the development of electrochemical biosensors for the determination of putrescine. PUO was immobilized by cross‐linking on screen‐printed carbon electrodes (SPCEs) containing tetrathiafulvalene (TTF) as mediator (TTF/SPCEs). Isothermal titration calorimetry was used for investigation of kinetic properties of immobilized PUO. These PUO/TTF/SPCEs showed a linear response range from 10 a 74 µM, a capability of detection of 10.1±0.6 µM (n=4, α=β=0.05) and a precision of 6.7 %. Octopus and zucchini samples have been analysed using HPLC as a reference technique.

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Laccase catalysed oxidation of syringic acid: Calorimetric determination of kinetic parameters

Cited by 16 publications

References 42 publications

The Role of Natural Laccase Redox Mediators in Simultaneous Dye Decolorization and Power Production in Microbial Fuel Cells

The Role of Natural Laccase Redox Mediators in Simultaneous Dye Decolorization and Power Production in Microbial Fuel Cells

Insights into laccase producing organisms, fermentation states, purification strategies, and biotechnological applications

Characterization of a Disposable Electrochemical Biosensor Based on Putrescine Oxidase from Micrococcus rubens for the Determination of Putrescine

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