• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.567-570
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• 2000

The condition of immobilization of the partially purified levan fructotransferase and the properties of the immobilized enzyme was investigated. Levan fructotransferase was immobilized on ${\kappa}\;-carrageenan$ beads by entrapment method. The optimal ${\kappa}\;-carrageenan$ concentration was obtained 2%(w/v) (or the matrix. At that time, immobilized enzymes(0.81 units) have relative low activity compare with soluble enzyme(7.7 units). To immobilized and soluble enzyme, optimal activity temperature and pH were measured $55^{\circ}C$, 6.0 in sodium phosphate buffer 20mM solution. If crosslinking agent was added, proper concentration was 0.5%(v/v). At $37^{\circ}C$, immobilized and soluble enzyme converted levan to oligofructose and DFA IV, and the conversion ratio was 32% and 61% at 60 hr.

• Journal of Life Science
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• v.23 no.12
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• pp.1471-1476
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• 2013

The present study deals with the immobilization of Kluyveromyces lactis ${\beta}$-galactosidase on a weak ionic exchange resin (Duolite A568) as polymer support. ${\beta}$-Galactosidase was immobilized using the adsorption method. A kinetic study of the immobilized enzyme was performed in a packed-bed reactor. The adsorption of the enzyme followed a typical Freundlich adsorption isotherm. The adsorption parameters of k and n were 14.6 and 1.74, respectively. The initial rates method was used to characterize the kinetic parameters of the free and immobilized enzymes. The Michaelis-Menten constant ($K_m$) for the immobilized enzyme (120 mM) was higher than it was for the free enzyme (79 mM). The effect of competitive inhibition kinetics was studied by changing the concentration of galactose in a recycling packed-bed reactor. The kinetic model with competitive inhibition by galactose was best fitted to the experimental results with $V_m$, $K_m$, and $K_I$ values of 46.3 $mmolmin^{-1}mg^{-1}$, 120 mM, and 24.4 mM, respectively. In a continuous packed-bed reactor, increasing the flow rate of the lactose solution decreased the conversion efficiency of lactose at different input lactose concentrations. Continuous operation of 11 days was conducted to investigate the stability of a long-term operation. The retained activity of the immobilized enzymes was 63% and the half-life of the immobilized enzyme was found to be 15 days.

• Journal of Microbiology and Biotechnology
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• v.18 no.3
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• pp.465-471
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• 2008

Highly active, stable, and magnetically separable immobilized enzymes were developed using carboxymethyl cellulose (CMC) and diethylaminoethyl cellulose DEAE-C; hereafter designated "DEAE" as supporting materials. Iron oxide nanoparticles penetrated the micropores of the supporting materials, rendering them magnetically separable. Lipase (LP) was immobilized on the surface of the supporting materials by using cross-linked enzyme aggregation (CLEA) by glutaraldehyde. The activity of enzyme aggregates coated on DEAE was approximately 2 times higher than that of enzyme aggregates coated on CMC. This is explained by the fact that enzyme aggregates with amine residues are more efficient than those with carboxyl residues. After a 96-h enantioselective ibuprofen esterification reaction, 6% ibuprofen propyl ester was produced from the racemic mixture of ibuprofen by using DEAE-LP, and 2.8% using CMC-LP.

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.159-162
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• 2005

In this paper, we report a novel technique for the manufacture of polymeric bar-coded strips having diverse characteristics such as sensing with biocatalysts using a microfluidic platform and 'on the fly' photopolymerization. This method is a very simple, cost-effective means for mass production, and diverse materials sensitive to hazardous environments such as enzymes, DNA, or antigens are expected to be immobilized stably, as the fabrication process does not need any hazardous environments. On the basis of this technology, we fabricated enzyme-immobilized barcoded strip for multiple bio-analysis.

• Journal of the Korean Wood Science and Technology
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• v.29 no.3
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• pp.112-122
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• 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%.

• Microbiology and Biotechnology Letters
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• v.13 no.2
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• pp.115-118
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• 1985

Rifamycin B oxidase converts rifamycin B to rifamycin S using oxygen as cosubstrate. Humnicola spp. (ATCC 20620) was treated with acetone and the cell powder was immobilized with cellulose acetate. The properties of the immobilized enzyme was examined. The optimum pHs of the immobilized and the free enzymes were 7.2. The optimum temperature of the immobilized enzyme was at 50-55$^{\circ}C$, which was 5$^{\circ}C$ higher than that of the free enzyme. The activities of the immobilized enzyme appeared less sensistive with respect to the changes of temperature and pH as compared to those of the free enzyme. Twenty percent of the enzyme activity was recovered when the enzyme was immobilized in 3mm beads. The storage stability was good below 4$0^{\circ}C$, but the activity decreased very rapidly above 5$0^{\circ}C$. The physical strength of the beads was good and was suitable as packing material in a three-phase enzyme reactor.

• KSBB Journal
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• v.18 no.5
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• pp.377-384
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• 2003

On-line monitoring techniques for fumaric acid and succinic acid were developed by flow injection analysis (FIA). For the determination of fumaric acid, two enzymes, fumarase and malic dehydrogenase were immobilized on VA-epoxy Biosynth E3-carrier and integrated into a FIA-system with a fluorescence detector. For the analysis of succinic acid, isocitrate lyase and isocitrate dehydrogenase were also immobilized on VA-epoxy polymer support and used in a FIA system. The immobilized enzymes in two FIA systems were characterized systematically, e.g. optimum pH and temperature, inhibitory effects etc. Two FIA systems were also used to on-line monitor the concentrations of fumaric acid and succinic acid in biotechnological processes. Good agreement between on-line monitored data and off-line data measured by HPLC showed extensive application of the FIA systems in bioprocesses.

• Journal of Microbiology and Biotechnology
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• v.25 no.11
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• pp.1773-1781
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• 2015

Environmental security is one of the major concerns for the safety of living organisms from a number of harmful pollutants in the atmosphere. Different initiatives, legislative actions, as well as scientific and social concerns have been discussed and adopted to control and regulate the threats of environmental pollution, but it still remains a worldwide challenge. Therefore, there is a need for developing certain sensitive, rapid, and selective techniques that can detect and screen the pollutants for effective bioremediation processes. In this perspective, isolated enzymes or biological systems producing enzymes, as whole cells or in immobilized state, can be used as a source for detection, quantification, and degradation or transformation of pollutants to non-polluting compounds to restore the ecological balance. Biosensors are ideal for the detection and measurement of environmental pollution in a reliable, specific, and sensitive way. In this review, the current status of different types of microbial biosensors and mechanisms of detection of various environmental toxicants are discussed.

• KSBB Journal
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• v.21 no.4
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• pp.279-285
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• 2006

We investigated the effects of immobilization chemistry on the yield of immobilization and the bioactivity of the immobilized enzymes. Trypsin as a model protein and macroporous polymer beads(Toyopearl AF 650M, Tosho Co., Japan) was used as a model matrix. Four methods were used to immobilize trypsin; covalent conjugation by reductive amination(at pH 10.0 and pH 4.0) and affinity interaction via streptavidin-biotin, and double-affinity interaction via biotin-streptavidin-biotin system. The covalent conjugation immobilized $3{\sim}4$ mg/ml-gel, ca. 3-fold higher than the affinity method. However, the specific activity of the covalently(pH 10.0) and affinity-immobilized trypsin(via streptavidin-biotin) are ca. 37% and 50%, respectively, of that of the soluble enzyme(on the low-molecular-weight BAPNA substrate). When the molecular size of a substrate increased, the affinity-immobilized trypsin showed higher clavage activity on insulin and BSA. This result seemed to indicate the streptavidin-biotin system allowed more steric flexibility of the immobilized trypsin in its interaction with a substrate molecule. To confirm this, we studied the molecular flexibility of immobilized trypsin using quartz crystal microbalance-dissipation. Self-assembled monolayers were formed on the Q-sensor surface by aminoalkanethiols, and gultaraldehyde was attached to the SAMs. Trypsin was immobilized in two ways: reductive amination(at pH 10.0) and the streptavidin-biotin system. The dissipation shift of the affinity-immobilized trypsin was $0.8{\times}10^{-6}$, whereas that of the covalently attached enzyme was almost zero. This result confirmed that the streptavidin-biotin system allowed higher molecular flexibility. These results suggested that the bioactivity of the immobilized enzyme be strongly dependent on its molecular flexibility.

• KSBB Journal
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• v.13 no.2
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• pp.147-154
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• 1998

Enzymatic hydrolysis using an immobilized enzyme was carried out to produce chitosan oligosaccharides (COSs) from chitosan effectively. Chitosanase was immobilized on eight different carriers by physical adsorption. The enzyme immobilized on chitin had higher activity than those immobilized on the other carriers in spite of its lower adsorption. The activity of chitin-immobilized enzyme was more than 90% of the original activity. Optimal temperature of the immobilized enzyme increased by about $15^{\circ}C$ and its thermostability was excellent in relatively wide range of temperature. But its effects of pH did not improve compared to the free enzyme. The immobilized enzyme produced 153 mg/g chitosan of the reducing sugar for 3hrs of hydrolytic incubation time. The total content of higher oligomers, tetramer to hexamer, among amount of total COSs obtained for 2hrs was more than 90%. In kinetic parameters for both enzymes, immobilized enzyme showed lower affinity for substrate and reaction rate than free enzyme, however, no reduction of the rate for high substrate concentrations. Consequently, chitin-immobilized could effectively hydrolyse chitosan and produce the higher COSs without activity decrease in comparison with the free enzyme.