• Journal of Microbiology and Biotechnology
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• v.4 no.2
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• pp.85-94
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• 1994

Lipase (triacylglycerol hydrolase, EC 3.1.1.3) is able to catalyze the hydrolysis of ester bonds of triacylglycerols at the interface between aqueous phase and organic phase containing substrate. With the rapid development of lipid biotechnology, lipase-catalyzed hydrolysis of lipids has a great concern from the industrial point of view. Owing to the reversible nature of the lipase, the reactions are also applied for glyceride synthesis, interesterification and resolution of racemic mixtures into optically active alcohols or acids. For all applications of the lipases, a reliable method for the determination of enzyme activity is required. Precise quantitative determination of its activity is essential as the basis of research and development of the bioprocess involving the enzyme. This article reviews the existing literature on the detection and determination of lipase activity from microbial, mammalian and plant sources.

• Journal of Microbiology and Biotechnology
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• v.6 no.6
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• pp.407-413
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• 1996

A novel type of extracellular phospholipase $A_1$ was isolated from Serratia sp. MK1 and purified to homogeneity by ammonium sulfate precipitation, anion exchange and gel filtration chromatography. The purified enzyme was a monomer with a molecular mass of about 43, 000 Da. This enzyme showed the highest lipolytic activity toward phosphatidylserine among the phosphoglycerides tested, and preferentially catalyzed the hydrolysis of the ester bond in phosphatidic acid to lyso-phosphatidic acid. Enzyme activity was completely inhibited by the addition of a chelating agent such as EDTA, and inhibited enzyme activity was fully recovered by the presence of $Ca^{2+}$. This implies that the enzyme requires $Ca^{2+}$ for activity. The enzyme was stable up to $70^{\circ}C$ when incubated for 1 h at pH 8.5, and the optimal pH and temperature were 8.5 and $50^{\circ}C$, respectively.

• Journal of the Korean Wood Science and Technology
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• v.38 no.2
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• pp.140-148
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• 2010

This study was to investigate the enzymatic hydrolysis of cellulose using the cellulase from whole body of the native termite collected in Milyang-si, Kyungsangnamdo, Korea. In the results, optimal temperature and pH for the enzyme of native termites were $45^{\circ}C$ and pH 5.5 for both endo-${\beta}$-1, 4-glucanase and ${\beta}$-glucosidase. Enzyme activity of the termite enzyme was shown $8.8{\times}10^{-2}\;FPU/m{\ell}$. And the highest glucose hydrolysis rate of cellulose by the digestive enzyme from test termites was 24.5% based on the glucan, comparing 59.7% by commercial enzyme (only celluclast 1.5 L) at 1% (w/v) substrate and 36 hours in hydrolysis time. This hydrolysis rate by the digestive enzyme from test termites was comparatively high value in 41% level of the commercial enzyme. When cellulose was hydrolyzed by the digestive enzyme of the native termite, glucose hydrolysis was almost completed in 12 hours which was the considerably reduced time for cellulose hydrolysis. It was suggested that the quiet short reaction time for cellulose hydrolysis by the enzyme from native termite could be a very high advantage for development of hydrolysis cellulase for lignocellulosic biomass.

• Mycobiology
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• v.39 no.4
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• pp.278-282
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• 2011

The objective of this study was to find useful fungi with ${\alpha}$-amylase activity from the Korean traditional nuruk for the quality of traditional Korean alcoholic beverage. In this study, 165 samples of traditional nuruk were collected from 170 regions throughout Korea and the fungi were isolated to a total of 384 strains. In order to investigate the effect of microflora on nuruk, ${\alpha}$-amylase activity, saccharogenic power (SP), starch hydrolysis activity and acid producing activity were evaluated. Ten strains were selected by ${\alpha}$-amylase activity, which ranged from 458.47 to 1,202.75 U/g. The size of the discolored zone for the starch hydrolysis activity of each fungus ranged from 0.3 to 2 cm. The SP of the 10 strains ranged from 228.8 to 433.4 SP. Of the 10 stains, three were identified as Aspergillus oryzae, two as Aspergillus flavus, two as Lichtheimia sp., one as Rhizopus oryzae and two as other strains. The total aflatoxins present in the nuruks were examined using enzyme-linked immunosorbent assay. The 10 nuruks had less than 1.11 ppb of aflatoxins.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.4
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• pp.343-352
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• 2022

Co/Al₂O₃ nanopowder was used as a catalyst to investigate the effect of catalyst support, reduction temperature, sodium borohydride (NaBH₄) concentration, sodium hydroxide (NaOH) concentration, and reaction temperature on the characteristics of NaBH₄ hydrolysis. The Co/Al₂O₃ nanopowder showed a high catalytic activity among various catalysts. Catalyst reduction at 250℃ exhibited a relatively good activity. The activity decreased with an increase in the NaBH₄ concentration. Conversely, the activity increased and then decreased with an increase in the NaOH concentration. Additionally, the activity increased with an increase in the reaction temperature. The value of apparent activation energy was 40.81 kJ/mol, which was lower than the other Co-based catalysts. Thus, Co/Al₂O₃ nanopowder catalyst can be widely used for NaBH₄ hydrolysis owing to its superior catalytic activity.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.8
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• pp.1031-1037
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• 2007

Changes in red ginseng fusion cheonggukjang properties under various hydrolytic conditions were investigated for its possible application to different types of food products. Among the four types of protease that were analyzed, protease (KMF -G) produced the highest hydrolysis rate, calcium binding capacity, and total phenolic compound content. In addition, the highest fibrinolytic activity and ACE inhibitory activity were also exhibited at 87.10 units and 67.17%, respectively. Among a number of different protease concentrations, a 0.02% concentration of protease (KMF-G) was found to be appropriate for the purposes of the study. The best results for red ginseng cheonggukjang hydrolysis were observed at the 60 and 90 min intervals. However, there was not a significant difference between the results at the two time points. The unpleasant odor and bitter taste associated with red ginseng fusion cheonggukjang improved with hydrolytic activity exceeding 60 min. Thus, the optimal hydrolysis time was determined to be 60 min. The total ginsenoside content of red ginseng cheonggukjang was 9.197 mg/g and the hydrolysate content was 11.707 mg/g. Based on the results, it was determined that the addition of 0.02% protease (KMF -G) and treatment for 60 min are the optimal hydrolytic conditions for red ginseng cheonggukjang to improve its biochemical characteristics, including fibronolytic activity and ACE inhibitory activity.

• Journal of Microbiology
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• v.37 no.2
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• pp.59-65
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• 1999

RecA protein can promote strand assimilation, homologous pairing, and strand exchange. All these reactions require DNA-dependent ATP hydrolysis by recA protein, and the activities of recA protein are affected by the ionic environment. In this experiment, DNA-dependent ATPase activity showed different sensitivity to anionic species. ATP hydrolysis and strand exchange were relatively sensitive to salt in the reactions with NaCl, strongly inhibited at 100 mM NaCl. However, the inhibition by sodium acetate or sodium glutamate was not observed at 50∼100 mM concentration. Addition of sodium glutamate to the standard reaction condition increased the apparent efficiency of ATP hydrolysis during strand exchange. The condition including 50∼100 mM sodium-glutamate might be similar to the physiological condition.

• Journal of Applied Biological Chemistry
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• v.49 no.3
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• pp.86-89
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• 2006

The novel tetranuclear nickel (II) complex is a high rate accelerator in promoting hydrolysis of phosphate diesters. Nickel-bound bis-nitrophenyl phosphate (BNPP) can be $10^4$ times more reactive than the unbound BNPP. The large rate of enhancements by the complex slightly under basic condition has shown high catalytic activity in phosphate diester cleavage. The bell-shaped pH-rate profile indicated that the nickel-oxide form of the tetranuclear complex or its kinetic equivalent was the active species for cleaving BNPP. The catalytic hydrolysis between tetranuclear nickel (II) complex and phosphate diester proceeds via the formation of bidentate coordination of the anionic phosphate to the Ni (II) atom. This reveals that the complex has the possibility as artificial nuclease.

• Biotechnology and Bioprocess Engineering:BBE
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• v.8 no.5
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• pp.306-308
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• 2003

Enantioselective hydrolysis for the production of chiral styrene oxide was investigated using the epoxide hydrolase activity of a newly isolated Rhodosporidium kratochvilovae SYU-08. The effects of reaction parameters - buffer type, pH, temperature, initial substrate concentrations, phenyl-1,2-ethanediol concentrations on hydrolysis rate, and enantioselectivity - were analyzed. Optically active (S)-styrene oxide with an enantiomeric excess higher than 99 % was obtained from its racemate. with a yield of 38 % (theoretically 50% maximum yield) from an initial concentration of 80 mM.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.3
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• pp.427-433
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• 1995

The optimal condition for hydrolysis of oyster was evaluated with proteases using response surface methodology(RSM). Among 11 commerical proteases, APLTM 440 was selected as the suitable protease for producing oyster hydrolysate on the basis of cost per unit enzyme activity. The effect of autolysis on degree of hydrolysis in oyster was negligible comparing to that of APL 440 protease treatment. From RSM and ridge analysis, the conditions favoring the highest degree of hydrolysis were pH 9.95, 61.1$^{\circ}C$, 2.64 hr reaction time, 49.2% substrate, and 0.35% enzyme/substrate ratio. Oyster hydrolysate prepared under optimal conditions shwoed virtually 51.98% of hydrolysis.