• KSBB Journal
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• v.25 no.5
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• pp.453-458
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• 2010

The magnetically separable polyaniline nanofiber enzymes were developed for the recycle of enzyme and enhanced enzyme stability. The stability of enzyme was maintained over 90% for 8 days under room temperature and vigorous shaking conditions (200 rpm). The residual activity of immobilized enzyme was over 60% after 8 days incubation at $55^{\circ}C$. Glucose was produced from various polysaccharides, agarose, curdlan, cellulose, and sea weed, using magnetically separable immobilized enzyme. Glucose production rate with curdlan was 1.2 g/(l h) and showed high decomposition rate due to high mass transfer. After 10 times recycle, the residual activity of immobilized enzyme was over 75%. 1 g/L of glucose was produced with 5 mg of immobilized enzymes.

• Korean Chemical Engineering Research
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• v.49 no.4
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• pp.387-392
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• 2011

Enzymes are being used in various fields due to their unique property of substrate specificity. Enzyme-linked immunosorbent assay(ELISA) has enabled the detection of various antigens by reporting the binding event of antigen and antibody via enzyme-catalyzed reaction. However, the sensitivity improvement of conventional ELISA has been limited because only one enzyme molecule is conjugated to one molecule of antibody. To overcome this limitation and further improve the sensitivity of ELISA, there have been efforts to increase the number ratio of enzymes to antibody. Recently, the nanobiocatalytic approaches, with their successful enzyme stabilization, improved the performance stability as well as sensitivity in a modified protocol of ELISA. The present paper introduces the basic principle of ELISA, and the recent efforts to improve sensitivity and performance stability of ELISA by using the nanobiocatalytic approaches.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1978.10a
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• pp.206.4-206
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• 1978

By utilizillg whole cell enzyme of the Xantho-monas citri IFO 3835, cephalexin is synthesized directly from 7-amino-deacetoxy cephalosporanic acid (7-ADCA) and phenyl glycine methyl ester (PGM). To date, cephalexin has been manufactu-red by chemical process involving fairly large number of steps to protect the amino group of phenly glycine and carboxyl group of 7-ADCA. However, the enzymatic process involves only a single step with 85％ conversion in 90 minutes. The fermentation variables studied indicate that oxygen transfer is limiting step in the enzyme production. Optimum conditions for enzymatic reaction were 37 C, pH 6.0, and the optimum substrate molar ratio of PGM to 7-ADCA was 2. Other variables that are related to the biochemical properties of whole cell enzyme temperature stability, pH stability, kinetic constants, reusing effect, enzyme loading effect were also evaluated.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1500-1506
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• 2011

Tyrosinase is a widespread enzyme with great promising capabilities. The Lineweaver-Burk plots of the catecholase reactions showed that the kinetics of mushroom tyrosinase (MT), activated by $Co^{2+}$ and $Zn^{2+}$ at different pHs (6, 7, 8 and 9) obeyed the non-essential activation mode. The binding of metal ions to the enzyme increases the maximum velocity of the enzyme due to an increase in the enzyme catalytic constant ($k_{cat}$). From the kinetic analysis, dissociation constants of the activator from the enzyme-metal ion complex ($K_a$) were obtained as $5{\times}10^4M^{-1}$ and $8.33{\times}10^3M^{-1}$ for $Co^{2+}$ and $Zn^{2+}$ at pH 9 and 6 respectively. The structural analysis of MT through circular dichroism (CD) and intensive fluorescence spectra revealed that the conformational stability of the enzyme in these pHs reaches its maximum value in the presence of each of the two metal ions.

• The Korean Journal of Food And Nutrition
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• v.13 no.4
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• pp.348-352
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• 2000

The stabilization of wheat $\beta$-amylase( Himaltosin GL, Hankyu-Bio) was attained by modification wish periodate-oxidized soluble starch. The specific activities of modified enzyme at pH 9.7 and pH 8.0 were 17% and 96%, respectively, compared with that of native enzyme. The pH stability of modified enzyme was increased at pH 2~5 and 6~12 in the presence of $\alpha$-cyclodextrin( $\alpha$-CD) compared with that of native enzyme, and optimum pH of the enzyme was changed from pH 5.0 to pH 7.0 by the modification. Thermal stability of the modified enzyme was increased. After treatment at 6$0^{\circ}C$ for 10min, the activity remained 8% for the enzyme modified at pH 8.0 in the presence of $\alpha$-CD and tested in the presence of $\alpha$-CD, 5% for the native enzyme. The native enzyme and modified enzyme showed one peak in HPLC. The molecular weight of the modified enzyme was slightly increased in HPLC analysis.

• BMB Reports
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• v.37 no.4
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• pp.394-401
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• 2004

The purpose of this paper is to suggest that the prominence of Haldane's explanation for enzyme catalysis significantly hinders investigations in understanding enzyme structure and function. This occurs despite the existence of much evidence that the Haldane model cannot embrace. Some of the evidence, in fact, disproves the model. A brief history of the explanation of enzyme catalysis is presented. The currently accepted view of enzyme catalysis -- the Haldane model -- is examined in terms of its strengths and weaknesses. An alternate model for general enzyme catalysis (the Shifting Specificity model) is reintroduced and an assessment of why it may be superior to the Haldane model is presented. Finally, it is proposed that a re-examination of many current aspects in enzyme structure and function (specifically, protein folding, x-ray and NMR structure analyses, enzyme stability curves, enzyme mimics, catalytic antibodies, and the loose packing of enzyme folded forms) in terms of the new model may offer crucial insights.

• Korean Chemical Engineering Research
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• v.44 no.1
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• pp.92-96
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• 2006

Enzymes in organic media afford many advantages such as chiral synthesis and resolution, modification of fats and oils and production of biodegradable polymers. However, the nature of solvents influences the activity and stability of enzymes, and the presence of organic solvents always constitute a risk of enzyme inactivation. Heat-shock protein Hsp90, one of the molecular chaperone, was applied for understanding of enzyme inactivation and for increasing of enzyme stability in water-miscible organic solvent. Hsp90 showed stabilization effect on HRP in the 30％ of DMSO, in the 30％ and 50％ of dioxane. Hsp90 also showed reactivation effect on the inactivated HRP by water-miscible organic solvent such as dioxane and DMSO. In addition, structural analysis using fluorescence spectrophotometry and circular dichroism showed that exposure of HRP in water-miscible organic solvent caused appreciable conformational changes and enzyme inactivation, and the unfolded HRP by water-miscible organic solvent was refolded by Hsp90.

• The Korean Journal of Food And Nutrition
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• v.13 no.4
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• pp.342-347
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• 2000

The stabilization of barley $\beta$-amylase(Biozyme ML, Amano) was attained by modification with periodate-oxidized soluble starch. The specific activities of modified enzyme at pH 9.7 and pH 8.0 were 42% and 92%, respectively, compared with that of native enzyme. The pH stability of modified enzyme was increased at pH 2~5 and 7~12 in the presence of $\alpha$-cyclodextrin( $\alpha$ -CD) compared wish that of native enzyme. Thermal stability of the modified enzyme was increased. After treatment at 6$0^{\circ}C$ for 10min. the activity remained 8% for the enzyme modified at pH 8.0 in the presence of $\alpha$-CD, 4.5% for the native enzyme. The native enzyme and modified enzyme showed two peak in HPLC. The molecular weight of the modified enzyme was slightly increased in HPLC analysis.

• Journal of Microbiology and Biotechnology
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• v.23 no.2
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• pp.205-210
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• 2013

Thiol-ene polymerization is a versatile tool for several applications. Here we report the preparation of epoxide groups containing thiol-ene photocurable polymeric support and the covalent immobilization of ${\alpha}$-amylase onto these polymeric materials. The morphology of the polymeric support was characterized by scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) coupled with SEM was used to explore the chemical composition. The polymeric support and the immobilization of the enzyme were characterized by FTIR analysis. SEM-EDS and FTIR results showed that the enzyme was successfully covalently attached to the polymeric support. The immobilization efficiency and enzyme activity of ${\alpha}$-amylase were examined at various pH (5.0-8.0) and temperature ($30-80^{\circ}C$) values. The storage stability and reusability of immobilized ${\alpha}$-amylase were investigated. The immobilization yield was $276{\pm}1.6$ mg per gram of polymeric support. Enzyme assays demonstrated that the immobilized enzyme exhibited better thermostability than the free one. The storage stability and reusability were improved by the immobilization on this enzyme support. Free enzyme lost its activity completely within 15 days. On the other hand, the immobilized enzyme retained 86.7% of its activity after 30 days. These results confirm that ${\alpha}$-amylase was successfully immobilized and gained a more stable character compared with the free one.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.1
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• pp.57-63
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• 2000

To extract insoluble proteins from abolished soybean meal, the meal was treatesd with phytase and protease produced by Aspergillus sp. SM-15 and Aspergillus sp. MS-18. The extraction of insoluble soybean protein was increased at alkaline range more than pH 5 in case of phytase, pH 7 to 11 in case of protease and pH 5 to 12 in case of the mixed enzyme of phytase and protease. The optimum extraction temperature of insoluble protein was 5$0^{\circ}C$ for phytase and the mixed enzyme of phytase and protease, and 6$0^{\circ}C$ for protease. The optimum treatment time for extraction of protein was 9 hrs for phytase, 11 hrs for protease and the mixed enzyme of phytase and protease and optimum unit of enzyme for extraction of protein was 600 unit, 40 unit and 900 unit＋60 unit in case of phytase, protease, phytase and protease, respectively. The treatment of mixed enzyme showed higher extracton rate of protein than single enzyme treatment. The foaming capacity, foaming stability, emulsion capacity, and emulsion stability of soybean meal protein by the treatment of the enzymes increased at all pH range. Further more oil absorption as well as water absorption capacities by the treatment of the enzymes were also increased. The functional properteis of the soybean meal protein treated by the mixed enzyme were higher than those of soybean meal protein treated by the single enzyme.