• Bulletin of the Korean Chemical Society
• /
• 제23권7호
• /
• pp.985-989
• /
• 2002

For efficient biopulping process, very active and stable lignase is essential. Laccase is one of the best enzyme in terms of environmentally benign processes, since the enzyme uses oxygen as an oxidant to degrade lignin and produces no hamful prod ucts. We could purify a laccase homogeneously from Cerrena unicolor in a very active state. It shows characteristic absorption feature with blue band at λmax = 604 ㎚. Molecular weight of the enzyme is 57,608 which could be accurately determined by MALDI/TOF MS. The enzyme has 2.8 copper ions per enzyme implying apoenzymes might exist together. The enzyme is active in lignin degradation and the activity increases 4 times in the presence of ABTS as a mediator.

• 한국환경보건학회지
• /
• 제30권2호
• /
• pp.79-83
• /
• 2004

The oxidative degradation of BPA with laccase from Trametes versiclor was conducted in a closed, temperature controlled system containing acetate buffer for pH control. The effects of medium pH, buffer concentration, temperature and mediator on degradation of BPA were investigated. The inactivation of the enzyme by temperature and reaction product was also studied. The optimal pH for BPA degradation showed about 5. Buffer concentration did not affect BPA degradation. On the other hand, the enzyme stability was higher at low concentration buffer(25 mM). Temperature rise increased the degradation rate of BPA up to 45$^{\circ}C$. The valuable mediator of laccase for BPA was ABTS. Elevated temperature and reaction product irreversibly inactivated the enzyme.

• 한국환경보건학회지
• /
• 제31권4호
• /
• pp.241-245
• /
• 2005

Laccase catalyzes the oxidation and polymerization of aromatic compounds in the presence of molecular oxygen. Studies were conducted to characterize the use of polyethylene glycol (PEG) as an additive to keep up the enzymatic stability. The enzymatic activities highly remained and bisphenol A (BPA) was rapidly converted in the presence of 5 mg/l of PEC. These effects were accomplished with PEG of molecular weight 3,350. A linear relationship was found between the quantity of BPA to be converted $(10-120\;{\mu}M)$ and the optimum dose of PEC required for greater than $95\%$ conversion. This result suggests that it is the interaction between the PEG and the reaction products. In the optimum dose of PEG, the aeration of reaction mixture neither enhanced the conversion of BPA nor retarded the inactivation of the enzyme.

• Journal of the Korean Wood Science and Technology
• /
• 제31권3호
• /
• pp.11-16
• /
• 2003

On nitrobenzene oxidation of aspen, spruce, and knauf wood meals gave rise to vanilline, syrigaldehyde, p-hydroxybenzoaldehyde, vanillic acid, and other minor oxidation products. The phenolic aldehydes (p-hydroxybenzaldehyde, vanilline, and syringaldehyde) are derived from oxidative degradation of the corresponding 4-hydroxyphenylpropane units and their ethers. The lignin content of knauf wood meals was different as the concentration of NaOH solution and cooking temperature. The lignin contents of aspen, spruce, and knauf wood meals were decreased as laccase treatment. The laccase caused C-oxidation, demethylation, cleavage in phenolic groups and C-C cleavage in syrigyl structures.

• 미생물학회지
• /
• 제46권1호
• /
• pp.93-95
• /
• 2010

리그닌 분해효소 군을 가진 백색부후균들은 다핵방향족 화합물을 포함하여 염료와 폭약 및 내분비장애 물질의 분해 등 다양한 난분해성 물질을 분해할 수 있다. 리그닌 분해효소 중 laccase와 manganese peroxidase (MnP)를 각각 발현하는 벡터를 국내에서 분리한 백색부후균류의 하나인 아교버섯(Phlebia tremellosa)에 형질전환 방법으로 도입시킨 형질전환체를 사용하여 염료의 탈색능력을 분석하였다. Methyl green의 경우 3일 후 약 50%의 탈색을 보인 야생형에 비하여 laccase 형질전환체(TF2-1)와 MnP 형질전환체(T5) 모두 90% 이상의 탈색을 보였다. Remazol brilliant blue R (RBBR)에서는 야생형이 약 67%의 탈색을 보인 반면 두 가지 형질전환체들은 약 85%의 탈색을 보였다. 각각의 형질전환체들은 laccase와 MnP의 활성 및 유전자 발현도 활발한 것으로 확인되었다.

• Journal of the Korean Wood Science and Technology
• /
• 제29권3호
• /
• pp.112-122
• /
• 2001

Laccase enzymes from Cerrena unicolor and Trametes versicolor were immobilized on the activated glass beads (CPG), silica gel (SG) and soil (SL). The heterogeneous matrices were activated by ${\gamma}$-aminopropyltriethoxysilane (APTES) and glutaraldehyde (GA), and their surfaces were coated by keratin (KER) on activated or non-activated CPG, SG and SL. The laccase activities were tested in the aqueous solution for the native and immobilized preparations using different pH and temperature conditions. By keratin coating on supports, in the cases of CPG-KER and SL-KER, the immobilization yield was increased from about 80% to 90%. Moreover, much less protein was immobilized in keratin coated matrices than in inorganic ones alone (e.g. on CPG-KER 57.6%, whereas on CPG alone 80.6%). Laccase immobilization on keratin coated inorganic matrices was generally more effective than that of non-coated matrices. Concerned to pH dependency, the optima pH for immobilized laccases generally shifted towards to higher values, 5.5-5.8 and even 5.9 in the case of keratin for C. unicolor and from 5.3 to 5.7 for T. versicolor, respectively, and decreased less gradually both in acidic and alkaline regions. The immobilized laccase was more stable against thermal denaturation. This seems particularly true at $75^{\circ}C$ in the case of C. unicolor, where the activity of immobilized enzyme is > 50% higher than that of the free enzyme. For T. versicolor the respective values were $65^{\circ}C$, and 50%.

• 펄프종이기술
• /
• 제29권4호
• /
• pp.7-17
• /
• 1997

균체가 생산하는 laccase 효소가 다방면으로 이용되면서, 이 효소를 균체로부터 대량으로 생산하고 분리.정제하여야 할 필요성이 대두되고 있다. 아울러 이 효소의 활성을 유도하기 위한 inducer 로서 2,5-xylidine 이 주로 사용되고 있는바, 이 xylidine 의 유독성이 인정되면서 사람에게 독성을 주지 않는 환경친화적 inducer의 검색이 필요하게 되었다. 본 연구에서는 백색부후균 Cerrena unicolor가 분비하는 laccase 효소의 유도를 위한 inducer로서 ferulic acid를 사용하였으며, 균체로부터 생산 및 분리된 laccase 효소의 정제특성을 구명코자 하였다. 본효소(constitutive enzyme)로서 I 및 II를, ferulic acid를 inducer로 사용한 경우 inducing 효소 III을 분리.정제하였다. 본 효소 I 및 II의 Michaelis 정수는 각각 737 M, 716 M 이었고, inducing효소 III은 167 M 로서, 기질에 대한 높은 친화성을 보여주고 있다. 분자량도 각각 65 kD, 63 kD 였으며, inducing효소 III은 59 kD 였다. 두효소 모두 15-19%의 당 및 단백질분자당 4M의 동(Cu)을 함유하고 있었다. 정제효율은 효소 I 및 II가 10.1%, 9.4% 였으며, III은 3.2% 였다. 모든 효소의 최적 pH 는 5.5였으며, 최적온도는 비교적 높은 $40^{\circ}C$였다.

• Journal of Electrochemical Science and Technology
• /
• 제8권2호
• /
• pp.87-95
• /
• 2017

Enzymatic fuel cells are promising low cost, compact and flexible energy resources. The basis of enzymatic fuel cells is transfer of electron from enzyme to the electrode surface and vice versa. Electron transfer is done either by direct or mediated electron transfer (DET/MET), each one having its own advantages and disadvantages. In this study, the DET and MET of laccase-based biocathodes are compared with each other. The DET of laccase enzyme has been studied using two methods; assemble of needle-like carbon nanotubes (CNTs) on the electrode, and CNTs/Nafion polymer. MET of laccase enzyme also is done by use of ceramic electrode containing, ABTS (2,2'-azino-bis [3-ethylbenzthiazoline-6-sulphonic acid]) /sol-gel. Cyclic voltammetric results of DET showed a pair of well-defined redox peaks at $200{\mu}A$ and $170{\mu}A$ in a solution containing 5and $10{\mu}M$ o-dianisidine as a substrate for needle-like assembled CNTs and CNTs-Nafion composite respectively. In MET method using sol-gel/ABTS, the maximum redox peak was $14{\mu}A$ in the presence of 15 M solution o-dianisidine as substrate. The cyclic voltammetric results showed that laccase immobilization on needle-like assembled CNTs or CNTs-Nafion is more efficient than the sol-gel/ABTS electrode. Therefore, the expressed methods can be used to fabricate biocathode of biofuel cells or laccase based biosensors.

• Bulletin of the Korean Chemical Society
• /
• 제25권8호
• /
• pp.1195-1201
• /
• 2004

Tyrosinase was covalently immobilized on platinum electrode according to the method we developed for laccase (Bull. Korean Chem. Soc. 2002, 23(7), 385) and p-chlorophenol, p-cresol, and phenol could be detected with sensitivities of 334, 139 and 122 nA/ ${\mu}M$ and the detection limits of 1.0, 2.0, and 2.5 ${\mu}M$, respectively. The response time ($t_{90\%}$) is 3 seconds for p-chlorophenol, and 5 seconds for p-cresol and phenol. The optimal pHs of the sensor are in the range of 5.0- 6.0. This sensor can tolerate at least 500 times repeated injections of p-chlorophenol with retaining 80% of initial activity. In case of tyrosinase and laccase co immobilized platinum electrode, the sensitivities are 560 nA/ ${\mu}M$ for p-phenylenediamine (PPD) and 195 nA/ ${\mu}M$ for p-chlorophenol, respectively. The sensitivity of the bi-enzyme sensor for PPD increases 70% compared to that of only laccase immobilized one, but the sensitivity for p-chlorophenol decreases 40% compared to that of only tyrosinase immobilized one. The sensitivity increase for the bi-enzyme sensor for PPD can be ascribed to the additional catalytic function of the co-immobilized tyrosinase. The sensitivity decrease for p-chlorophenol can be explained by the “blocking effect” of the co-immobilized laccase, which hinders the mass transport through the immobilized layer. If PPD was detected with the electrode that had been used for p-chlorophenol, the sensitivity decreased 20% compared to that of the electrode that had been used only for PPD. Similarly, if p-chlorophenol was detected with PPD detected electrode, the sensitivity also decreased 20%. The substrate-induced conformation changes of the enzymes in a confined layer may be responsible for the phenomena.

• 한국버섯학회지
• /
• 제16권4호
• /
• pp.272-278
• /
• 2018

본 연구에서는 원목재배용 표고(Lentinula edodes) 품종에 대한 목질섬유소 분해능을 검정하였다. 5개의 국산품종(천백고, 산조 303호, 풍년고, 백화향, 수향고)을 대상으로 malt extract broth(MEB) 배지에 lignin의 첨가에 따른 RBBR(Remazol Brilliant Blue R) 탈색능을 조사한 결과, 산조 303호와 풍년고가 배양 5일째부터 우수한 분해능을 보였다. 섬유소 분해효소인 MnP와 laccase의 활성은 풍년고가 배양 7일째 MnP 활성이 2,809U/mg, laccase 활성이 2,230U/mg으로 나타났고, 산조 303호가 배양 11일째 MnP 활성이 2,673U/mg, laccase 활성이 2,049U/mg으로 최고 활성을 나타났으며, lignin을 첨가하였을 때 효소의 활성이 증가하였다. 산조 303호, 풍년고와 수향고는 배양 5주 만에 filter paper의 분해정도를 육안으로 확인이 가능할 정도로 분해능이 우수하였다.