Factors affecting the oxidative activity of laccase towards biphenyl derivatives in homogeneous aqueous-organic systems

Tominaga, Jo; Michizoe, Junji; Kamiya, Noriho; Ichinose, Hirofumi; Maruyama, Tatsuo; Goto, Masahiro

doi:10.1016/s1389-1723(04)70236-4

Cited by 19 publications

(9 citation statements)

References 21 publications

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“…The maximal reaction rate was obtained at pH 5 and 6. Interestingly, the degradation of dymron hardly progressed above pH 6, although the laccase/mediator system functions at neutral pH (8). This is probably due to the reactivity of the oxidized mediator and to the degradability of dymron at neutral pH.…”

Section: Resultsmentioning

confidence: 99%

“…(108,000 U/g) was kindly provided by Daiwa Kasei Co. Ltd. The definition of laccase activity (U/g) has been described elsewhere (8). Lipase PS (from Burkholderia cepacia), lipase A (from Aspergillus niger), lipase AK (from Pseudomonas fluorescence), lipase F (from Rhizopus oryzae), acylase from Aspergillus sp., protease A, and protease P were generously supplied by Amano Enzyme Inc. (Nagoya, Japan).…”

Section: Methodsmentioning

confidence: 99%

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Laccase-Mediated Oxidative Degradation of the Herbicide Dymron

et al. 2006

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The present study reports the successful and effective degradation of the persistent herbicide dymron catalyzed by the oxidative enzyme laccase in the presence of a reaction mediator (a laccase/mediator system). Using 2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) as the mediator, over 90% of dymron was degraded within 24 h, while the half-life of dymron is 50 days in soil. The results suggested that oxidation of dymron resulted in the production of decomposed compounds with a single aromatic ring. We also found that edible surfactants and a dishwashing detergent were useful to solubilize dymron in an aqueous solution and did not inhibit the oxidative degradation. Degradation proceeded at acidic pH and in a broad range of temperatures (303-353 K). The use of natural mediators also allowed the oxidative degradation of dymron to some extent. In conclusion, we propose the possible use of a laccase/mediator system for the treatment of soils and drainwater contaminated with herbicides.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Laccase-Mediated Oxidative Degradation of the Herbicide Dymron

et al. 2006

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“…and the conversion of 4-hydroxybiphenyl decreased with increasing DMSO concentrations. However, the study was only carried out for DMSO concentrations between 30 to 70%, as the substrate was not soluble below 30% [37]. We conclude from our data that DMSO up to 25% (v/v) can be used as a co-solvent for enhancing the solubility of hydrophobic substrates in biotransformations with CotA-type laccases.…”

Section: Discussionmentioning

confidence: 97%

Bacillus pumiluslaccase: a heat stable enzyme with a wide substrate spectrum

2011

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BackgroundLaccases are multi-copper oxidases that catalyze the one electron oxidation of a broad range of compounds. Laccase substrates include substituted phenols, arylamines and aromatic thiols. Such compounds are activated by the enzyme to the corresponding radicals. Owing to their broad substrate range laccases are considered to be versatile biocatalysts which are capable of oxidizing natural and non-natural industrial compounds, with water as sole by-product.ResultsA novel CotA-type laccase from Bacillus pumilus was cloned, expressed and purified and its biochemical characteristics are presented here. The molecular weight of the purified laccase was estimated to be 58 kDa and the enzyme was found to be associated with four copper atoms. Its catalytic activity towards 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS), 2,6-dimethoxyphenol (2,6-DMP) and syringaldazine (SGZ) was investigated. The kinetic parameters KM and kcat for ABTS were 80 ± 4 μM and 291 ± 2.7 s-1, for 2,6-DMP 680 ± 27 μM and 11 ± 0.1 s-1 and for SGZ only kcat could be estimated to be 66 ± 1.5 s-1. The pH optimum for ABTS was 4, for 2,6-DMP 7 and for SGZ 6.5 and temperature optima for ABTS and 2,6-DMP were found to be around 70°C. The screening of 37 natural and non-natural compounds as substrates for B. pumilus laccase revealed 18 suitable compounds. Three of them served as redox mediators in the laccase-catalyzed decolorization of the dye indigocarmine (IC), thus assessing the new enzyme's biotechnological potential.ConclusionsThe fully copper loaded, thermostable CotA laccase from Bacillus pumilus is a versatile laccase with potential applications as an industrial biocatalyst.

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“…Non-aqueous enzymology by means of medium-engineering has been proposed as alternative to common biotransformation reactions in industry [Stöcklein and Scheller 1995], and with a view to increasing applicability, the herein described crude PO from A. chroococcum SBUG 1484 was tested for activity in various organic solvents often used in biotransformation and biocatalysis. Generally, DMSO was determined as the most activity enhancing solvent presumably allowing the PO to retain its active confirmation [Tominaga et al 2004], whereas the protic solvents ethanol and methanol gave minimal inhibitory effects on activity. However, greatest decrease of Azotobacter PO activity recovered in crude extracts was monitored through addition of 15% acetonitrile, even though it is an aprotic polar solvent like DMSO.…”

Section: Discussionmentioning

confidence: 99%

Study of enzymatic properties of phenol oxidase from nitrogen-fixing azotobacter chroococcum

et al. 2011

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Azotobacter chroococcum is a widespread free-living soil bacterium within the genus of Azotobacter known for assimilation of atmospheric nitrogen and subsequent conversion into nitrogenous compounds, which henceforth enrich the nitrogen content of soils. A. chroococcum SBUG 1484, isolated from composted earth, exhibits phenol oxidase (PO) activity when growing under nitrogen-fixing conditions. In the present study we provide incipient analysis of the crude PO activity expressed by A. chroococcum SBUG 1484 within comparative analysis to fungal crude PO from the white-rot fungus Pycnoporus cinnabarinus SBUG-M 1044 and tyrosinase (PPO) from the mushroom Agaricus bisporus in an attempt to reveal desirable properties for exploitation with future recombinant expression of this enzyme. Catalytic activity increased with pre-incubation at 35°C; however 70% of activity remained after pre-treatment at 50°C. Native A. chroococcum crude PO exhibited not only strong preference for 2,6-dimethoxyphenol, but also towards related methoxy-activated substrates as well as substituted ortho-benzenediols from over 40 substrates tested. Presence of CuSO4 enhanced crude phenol oxidase activity up to 30%, whereas NaN3 (0.1 mM) was identified as the most inhibiting substance of all inhibitors tested. Lowest inhibition of crude PO activity occurred after 60 minutes of incubation in presence of 15% methanol and ethanol with 63% and 77% remaining activities respectively, and presence of DMSO even led to increasing oxidizing activities. Substrate scope and inhibitor spectrum strongly differentiated A. chroococcum PO activity comprised in crude extracts from those of PPO and confirmed distinct similarities to fungal PO.

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Factors affecting the oxidative activity of laccase towards biphenyl derivatives in homogeneous aqueous-organic systems

Cited by 19 publications

References 21 publications

Laccase-Mediated Oxidative Degradation of the Herbicide Dymron

Laccase-Mediated Oxidative Degradation of the Herbicide Dymron

Bacillus pumiluslaccase: a heat stable enzyme with a wide substrate spectrum

Study of enzymatic properties of phenol oxidase from nitrogen-fixing azotobacter chroococcum

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