• Journal of the Korean Wood Science and Technology
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• v.29 no.3
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• pp.104-111
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• 2001

There are some evidence that active enzymatic proteins, e.g. fungal laccase, exist in the naturally occured soil humus. This study was performed to investigate the covalent binding of fungal laccase to the humic acid-iron complex, and to measure laccase activity of immobilized ones. Seven methods were adopted to form the covalent binding of fungal laccase with soil humic acids complexed with iron. Using these seven methods it was possible to change the dimension of spacer arm between laccase and support, and also to regulate the mode of covalent binding of this enzyme. The spacer arm was regulated from 2C to 11C. There was not observed any straight relationship between the spacer arm longitude and the laccase activity after immobilization, but the binding mode more effective than the former. Three out of the seven methods gave the high activity of immobilized laccase, and which active products of laccase immobilization was stable up to 10 days after the process. It is indicated that natural soil condition might be prevented the laccase activation by the toxic influence of some phenolic humic compounds. It was shown, for the first time, the possibilities to obtain the high activity of fungal laccase by binding to humic acids, and especially in complex with iron.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1978.10a
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• pp.207.2-207
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• 1978

Arthrobacter simplex (ATCC 6946) was cultured, induced and immobilized in acrylamide polymer. The characteristics of the immobilized whole-cell enayme were studied using hydrocortisone as the substrate. The enzyme activity was increased during the incubation of the gel particle in 0.5％ peptone media. The ennzyme reaction kinetics of the Δ'-dehydrogenase (3-oxosteroid Δ'-oxydo reductase, E. C. 1.3.99.4) foliowed the Michaelis-Menten type. Km and Vm values were different significantly after immobilization of the cell. The optimum pH and temperature were changed, too. Nitrogen sources such as casitone, peptone or tryptone were good media for the enzyme reaction. And there was no need to add cofactors of the enzyme in the pre-sence of energy sources used in the test. The effect of metal ions on the enzyme activity was insignificant. Organic solvents were used increase the substrate concentration and there was no optimum solvent concentration depending on the substrate concentration.

• Preventive Nutrition and Food Science
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• v.3 no.1
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• pp.36-42
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• 1998

Ion-selective eleltrodes(ISEs) are simple electrodechemical devices for the direct measurement of ions in the samples. A novel potentiometric biosensor for the determination of L-Malate or D-isocitrate has been developed by using CO2-3 -ISE-FIA system was composed of a pump, an injector, a malic enzyme or isocitric dehydrogenase enzyme reactor, a CO2-3 -ISE, a pH/mV meter, and an integrater. The various factors, such as buffer capacity types of plstericizer and polymer, were optimized for the CO2-3 selectivity. In this novel CO2-3 --ISE-FIA system, the potential difference due to the amount of CO2-3 produced from each enzyme reaction was proportional to the amount of L-malate or D-isocitrate.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.147-150
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• 1999

In the case of immobilizing of glucose oxidase in organic polymer using electrosynthesis, the glucose oxidase obstructs charge transfer and mass transport during the film growth. This may lead to short chained polymer and/or make charge-coupling weak between the glucose oxidase and the backbone of the polymer. That is mainly due to insulating property and net chain of the glucose oxidase. Since being the case, it is useless to increase in amount of glucose oxidase more than reasonable in the synthetic solution. We establish qualitatively that amount of immobilization can be improved by adding a little ethanol in the synthetic solution. As ethanol was added by 0.1 rnol dm" in the synthetic solution, Michaelis-Menten constants of the resulting enzyme electrode decreased from 30.7 mmol $dm^{-3}$ to about 2 mmol $dm^{-3}$. That suggests increase in affinity of the enzyme electrode for glucose and in amount of the immobilized enzyme.zyme.

• Bulletin of the Korean Chemical Society
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• v.32 no.spc8
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• pp.3149-3151
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• 2011

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.485-489
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• 2003

Enzymatic hydrolysis of egg yolk Protein was carried out in continuous packed column reactor Five supports for enzyme immobilization were evaluated in this study. We investigated the optimum operation variables - pH, temperature, and flow rate in continuous reactor operation.

• 한국생물공학회:학술대회논문집
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• 2005.04a
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• pp.485-485
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• 2005

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2003.04a
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• pp.65-66
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• 2003

No Abstract, See Full Text

• Journal of Electrochemical Science and Technology
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• v.8 no.2
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• pp.87-95
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• 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.

• Journal of Microbiology and Biotechnology
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• v.31 no.3
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• pp.419-428
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• 2021

To efficiently recycle GH78 thermostable rhamnosidase (TpeRha) and easily separate it from the reaction mixture and furtherly improve the enzyme properties, the magnetic particle Fe3O4-SiO2-NH2-Cellu-ZIF8 (FSNcZ8) was prepared by modifying Fe3O4-NH2 with tetraethyl silicate (TEOS), microcrystalline cellulose and zinc nitrate hexahydrate. FSNcZ8 displayed better magnetic stability and higher-temperature stability than unmodified Fe3O4-NH2 (FN), and it was used to adsorb and immobilize TpeRha from Thermotoga petrophilea 13995. As for properties, FSNcZ8-TpeRha showed optimal reaction temperature and pH of 90℃ and 5.0, while its highest activity approached 714 U/g. In addition, FSNcZ8-TpeRha had better higher-temperature stability than FN. After incubation at 80℃ for 3 h, the residual enzyme activities of FSNcZ8-TpeRha, FN-TpeRha and free enzyme were 93.5%, 63.32%, and 62.77%, respectively. The organic solvent tolerance and the monosaccharides tolerance of FSNcZ8-TpeRha, compared with free TpeRha, were greatly improved. Using naringin (1 mmol/l) as the substrate, the optimal conversion conditions were as follows: FSNcZ8-TpeRha concentration was 6 U/ml; induction temperature was 80℃; the pH was 5.5; induction time was 30 min, and the yield of products was the same as free enzyme. After repeating the reaction 10 times, the conversion of naringin remained above 80%, showing great improvement of the catalytic efficiency and repeated utilization of the immobilized α-L-rhamnosidase.