• Bulletin of the Korean Chemical Society
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• v.23 no.3
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• pp.385-390
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• 2002

Laccase could be successfully assembled on an amine-derivatized platinum electrode by glutaraldehyde coupling. The enzyme layer formed on the surface does not communicate electron directly with the electrode, but the enzymatic activity of the surf ace could be followed by electrochemical detection of enzymatically oxidized products. The well-known laccase substrates, ABTS (2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)) and PPD (p-phenylenediamine) were used. ABTS can be detected down to 0.5 ${\mu}M$ with linear response up to 15 ${\mu}M$ and current sensitivity of 75 nA/ ${\mu}M.$ PPD showed better response with detection limit of 0.05 ${\mu}M$, linear response up to 20 ${\mu}M$, and current sensitivity of 340 nA/ ${\mu}M$ with the same electrode. The sensor responses fit well to the Michaelis-Menten equation and apparent $K_M$ values are 0.16 mM for ABTS and 0.055 mM for PPD, which show the enzymatic reaction is the rate-determining step. The laccase electrode we developed is very stable and more than 80% of initial activity was still maintained after 2 months of uses.

• Journal of the Korean Wood Science and Technology
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• v.28 no.4
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• pp.29-40
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• 2000

Highly purified Cerrena unicolor laccase (benzenediol:oxygen oxidoreductase, EC 1.10.3.2) caused the demethoxylation of milled wood lignin and several lignin related substances. The constitutive form of the enzyme produced extracellularly by C. unicolor fermenter culture was isolated and purified by ion-exchange chromatography on the DEAE-Toyopearl column and by affinity chromatography on a ConA-Sepharose and Syringyl-AH-Sepharose 4B columns. The enzyme was further immobilized on functionalized porous glass (CPG) and keratin coated CPG. The demethylating activity was monitored both by estimation of released methanol and by detection of the level of methoxyl groups (also in some water miscible solvents) after incubation of lignin materials with laccase preparations (free and immobilized). The effects of the incubation time and temperature on the demethoxylating activity of immobilized laccase preparations were also studied.

• Bulletin of the Korean Chemical Society
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• v.25 no.10
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• pp.1551-1554
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• 2004

In the presence of laccase, low molecular weight (M.W.) fractions from lignosulfonate (M.W. 97 kD) were produced. By Sephadex column chromatography, four lower M.W. fractions of 9 kD, 1.8 kD, 1 kD and 0.85 kD were identified. The addition of acetovanillone (AV) or acetosyringone (AS) enhanced to the degradation of lignosulfonate with fungal laccase. During this process, there were found new generation of lower M.W. fractions, e.g. approximately 20 kD, 1.8 kD, 1 kD and 0.85 kD for AV, and 20 kD, 3 kD, 1 kD and 0.85 kD for AS, respectively. The quantities of lower M.W. products (especially the fractions of M.W. 1 kD and 0.85 kD) were larger than those in the controls. Also, its degradation became more active in the presence of AS than AV. The presence of AS or AV seems to prevent the re-polymerization of degraded lignosulfonate by the laccase.

• The Korean Journal of Mycology
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• v.22 no.1
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• pp.46-49
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• 1994

When Coprinus congregatus was cultivated in low pH YpSs medium(pH 4.2), the culture supernatant turned brown earlier than that of normal(pH 7.1) medium resulted from the melanization synthesized by the secreted laccase reaction. The pH of medium became 5.2 after 24 h incubation. Laccase which was deeply related to the fungal development might also be implicated in the neutralization of excess hydrogen ions to protect from acidification of cytoplasm.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2010.04a
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• pp.79-92
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• 2010

In the presence of laccase, generation of monomeric aromatic acids from nonphenolic lignin model dimer veratrylglycerol-$\beta$-vanillate ether (VVE) was observed. The addition of acetovanillone (AV) or acetosyringone (AS) intensified this process, i.e. transformation was more extensive than in the experiments omitting mediators. Among the products isovanillic (IA) and vanillic (VA) acids were identified.

• Korean Journal of Microbiology
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• v.38 no.1
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• pp.54-56
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• 2002

Induction of laccase isozymes under acidic stresses were determined in Trametes versicolor, Pleurotus ostreatus and Ganoderma lucidum isolated in Korea, and in Lentinus squarrosulrs isolated in Thai. When cultures of these fungi were transferred to acidic liquid media (pH 3.0-4.0), the activities of secreted extralcellular laccases were increased 60% and 400% in T. versicolor and G. lucidum respectively. However, there was no such induction in L. squarrosulus or P. ostreatus. In L. squarrosulus, different laccase isozymes in the electrophoretic mobilities were induced under acidic conditions.

• Journal of the Korean Wood Science and Technology
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• v.32 no.3
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• pp.52-58
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• 2004

The use of N-hydroxyphthalimide (NHPI) as a mediator for laccase has proven to be comparable to N-hydroxybenzotriazole (HBT) for the delignification of kraft pulp, and the transformation of a number of industrial dyes. The advantages of NHPI derivatives are the biodegradation of these compounds compared to HBT, which has been shown to be recalcitrant in the environment, and the more reasonable cost of synthetic process.

• Mycobiology
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• v.43 no.1
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• pp.75-80
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• 2015

We identified single nucleotide polymorphism (SNP) markers in the laccase gene to establish a line-diagnostic system for shiitake mushrooms. A total of 89 fungal isolates representing four lines, including Korean registered, Korean wild type, Chinese, and Japanese lines, were analyzed. The results suggest that SNP markers in the laccase gene can be useful for line typing in shiitake mushrooms.

• Korean Journal of Microbiology
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• v.25 no.2
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• pp.148-156
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• 1987

Extracellular laccase (E.C. 1.10.3.2) from the culture filtrate of Pleurotus ostreatus was purified by ammonium sulfate precipctation, protamine sulfate precipitation, DEAE-Sephadex A-50 ion exchange chromatography and Sephadex G-100 gel permeation chromatography. The molecular weight of the enzyme was estimated by SDS-polyacrylamide gel electrophoresis to be 58,000 and the isoelectric point was 3.75. The optimum temperature for the enzyme was about $45^{\circ}C$ and the optimum pH was 6.5. The enzyme was found to be stable at temperature below $35^{\circ}C$ and rapidly inactivated at higher temperatures. Km values for ferulic acid, vanillic acid, dihydroxyphenylalanine (DOPA) were 48.6.$\mu$M, 0.52mM, and 2.73mM, respectively, which indicates that the enzyme has much higher affinity towards ferulic acid. The reaction products of the enzyme were separated by TLC and HPLC.

• Journal of Environmental Health Sciences
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• v.31 no.1
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• pp.61-65
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• 2005

The oxidative transformation of triclosan with laccase from Trametes versicolor was conducted in a closed, temperature controlled system containing phosphate buffer for pH control. The optimum pH for triclosan transformation showed about 5. Despite the observation that elevated temperatures tended to inactivate the enzyme, increased transformation of triclosan was observed up to $50^{\circ}C$. Of the mediators studied, ABTS was most successful at enhancing triclosan transformation. About 80% of the toxicity of the initial mixture was reduced after the enzymatic treatment. In the presence of 1.0 mM of anions such as sulfite, sulfide, and cyanide, triclosan transformation was greatly inhibited. Chloride and fluoride ions exhibited inhibition of triclosan transformation at 25 mM. Ferric ion substantially inhibited triclosan transformation at 1.0 mM.