• Journal of Applied Biological Chemistry
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• v.59 no.1
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• pp.75-81
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• 2016

Glutaraldehyde was used as a cross-linking agent for immobilization of purified ${\alpha}$-amylase from Exiguobacterium sp. DAU5. Befitting concentration of glutaradehyde and cross-linking time is the key to preparation of cross-linking chitosan beads. Based on optimized immobilization condition for ${\alpha}$-amylase, an overall yield of 56% with specific activity of 2,240 U/g on chitosan beads and 58% with specific activity of 2,320 U/g on chitosan-carbon beads was obtained. The optimal temperature and pH of each immobilized enzyme activity were $50^{\circ}C$ and 50 mM glycine-NaOH buffer pH 8.5, respectively. Those retained more than 75 and 90% of its maximal enzyme activity at pH 7.0-9.5 and after incubation at $50^{\circ}C$ for 1 h, respectively. In addition, the immobilization product showed higher organic-solvent tolerance than free enzymes. The mode of hydrolyzing soluble starch revealed that the ${\alpha}$-amylase possessed high hydrolyzing activity. These results indicate that chitosan is good support and has broad application prospects of enzyme immobilization.

• Archives of Pharmacal Research
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• v.19 no.5
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• pp.348-352
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• 1996

The antioxidant efficacy of aspalatone, a new antithrombotic agent, has been recognized in the neurotoxic model and in the cardiotoxic model in proliminary studies. We examined the specific activity of antiosidnat enzyme in the rat blood following administrations of aspirin, maltol, aspirin together with maltol, salicylmaltol (major metabolite of aspalatone) and aspalatone, respectively. Our assessment showed that salicylmaltol, maltol, aspalatone enhanced antiperoxidative activity. In addition, neither aspirin nor combination of aspirin and maltol, showed any significant effect on the activity of antioxidant enzyme. Because $H_{2}$$O_{2}$ accumulation may stimulate the thrombogenesis in blood, the result suggests that the induction of blood antiperoxidative activity produced by aspalatone may have beneficial effects on the thrombogenesis.

• The Korean Journal of Food And Nutrition
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• v.16 no.2
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• pp.152-157
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• 2003

Serratia marcescens ATCC 25419 protease was purified to homogeneity by ammonium sulfate treatment, and DEAE-cellulose anion exchange chromatography. The specific activity of the enzyme was increased 448-fold during purification with an overall yield of 43.0%. Metal reactivation on the purified protease from S. marcescens was studied. S. marcescens protease was a metalloenzyme to be completely inhibited its activity by EDTA and the enzyme outstandingly inhibited by Hg, Fe, Cu, but the activity was increased approximately 20% by Co. The reactivation of the apoenzyme was effective with Mn, Co, Zn in pH range from 6 to 8. Among metalloenzymes prepared to the addition of Mn, Co, Zn to restore the degree of activity of native enzyme, Zn-enzyme was similar to the native enzyme in respects with enzyme activity, alkali-inactivation, thermo-stability.

• Journal of Microbiology
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• v.44 no.3
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• pp.276-283
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• 2006

The thermophilic fungus Thermoascus aurantiacus 179-5 produced large quantities of a glucosidase which preferentially hydrolyzed maltose over starch. Enzyme production was high in submerged fermentation, with a maximal activity of 30 U/ml after 336 h of fermentation. In solid-state fermentation, the activity of the enzyme was 22 U/ml at 144 h in medium containing wheat bran and 5.8 U/ml at 48 h when cassava pulp was used as the culture medium. The enzyme was specific for maltose, very slowly hydrolyzed starch, dextrins (2-7G) and the synthetic substrate (${\alpha}$-PNPG), and did not hydrolyze sucrose. These properties suggest that the enzyme is a type II ${\alpha}$-glucosidase. The optimum temperature of the enzyme was $70^{\circ}C$. In addition, the enzyme was highly thermostable (100% stability for 10 h at $60^{\circ}C$ and a half-life of 15 min at $80^{\circ}C$), and stable within a wide pH range.

• YAKHAK HOEJI
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• v.41 no.6
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• pp.756-764
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• 1997

Ile-224 in I269S mutant horse liver alcohol dehydrogenase isoenzyme S (HLADH-S) was mutated to serine by site-directed mutagenesis in order to study the role of the residue in c oenzyme binding to the enzyme. The specific activity of the I269S and I224S mutant enzyme to ethanol was increased 6-fold and all Michaelis constants($K_a,\;K_b,\;K_p,\;and\;K_q$,/TEX>) were larger than those for the wild-type and I269S enzyme. The substitution decreased the afffinity to coenzymes and increased the specific activity of the enzyme. The mutant enzyme showed the highest catalytic efficiency for octanol among the primary alcohols. But it didn`t have activities on retinoids and 5${\beta}$-cholanic acid-3-one. From these results, it was confirmed that the hydrophobic interaction of Ile-224 residue with coenzyme was related to coenzyme affinity in ADH reaction. The substitution also affected the substrate affinities to the enzyme.

• Microbiology and Biotechnology Letters
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• v.23 no.5
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• pp.573-579
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• 1995

A Bacillus strain capable of producing an extracellular malto-oligosaccharides forming $\alpha $-amylase was isolated from soil and designated as Bacillus sp. SUH4-2. The enzyme was purified by ammonium sulfate fractionation, DEAE-Toyopearl and Mono-Q HR 5/5 column chromatographies using a FPLC system. The specific activity of the enzyme was increased by 16.1-fold and the yield was 13.5%. The optimum temperature for the activity of $\alpha $-amylase was 60-65$\circ$C and more than 50% of initial activity was retained after the enzyme was incubated at 60$\circ$C for 40 min. The enzyme was stable over a broad pH range of 5.0-8.0 and the optimum pH was 5.0-6.0. The molecular weight of the enzyme was determined to be about 63.6 kD and isoelectric point was around 5.8. The enzyme activity was strongly inhibited by Mn$^{2+}$, Ni$^{2+}$, and Cu$^{2+}$ ; slightly by Ca$^{2+}$. The purified enzyme produced starch hydrolyzates containing mainly maltose and maltotriose from soluble starch. The starch hydrolyzates were composed of 11% glucose, 59% maltose, 25% maltotriose and 5% maltotetraose.

• Journal of Applied Biological Chemistry
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• v.42 no.4
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• pp.169-174
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• 1999

Arabidopsis AHL gene contains 4 exons encoding a putative protein highly homologous to the yeast salt-sensitive enzyme HAL2, a 3'(2'),5'-bisphosphate nucleotidase involving in reductive sulfate assimilation. AHL cDNA complemented yeast met22 (hal2) mutant. AHL fusion protein expressed in E. coli exhibited $Mg^{2+}$-dependent, 3'-phosphoadenosine 5'-phosphate (PAP)-specific phosphatase activity. $Li^+,\;Na^+,\;K^+$ and $Ca^{2+}$ ions inhibit the enzyme activity by competing with $Mg^{2+}$ for the active site of the enzyme. The enzyme activity was also sensitive to ${\mu}M$ concentrations of toxic heavy metal ions such as $Cd^{2+},\;Cu^{2+}$ and $Zn^{2+}$, but was not recovered by addition of more $Mg^{2+}$ ions, suggesting that these ions inactivate the enzyme with a mechanism other than competition with $Mg^{2+}$ ions. Inhibition of the AHL enzyme activity may result in accumulation of PAP, which is highly toxic to the cell. Thus, the AHL enzyme could be one of the intial targets of heavy metal toxicity in plants.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.3
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• pp.280-286
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• 2021

This study was performed to screen the antimicrobial activities and proteolytic enzyme stability of the acidified extract of the Blue mussel Mytilus edulis. The acidified extract showed potent antimicrobial activities against Gram-positive bacteria, Bacillus subtilis, and Gram-negative bacteria, Escherichia coli D31, but had no activity against Candida albicans. Treatment of extract with trypsin completely abolished all or significant antibacterial activity against the tested bacteria, but slightly decreased antimicrobial activity against B. subtilis, and treatment of extract with chymotrypsin retained almost antibacterial activity against the tested bacteria except for E. coli D31. To confirm the additional enzyme stability of the extract, antimicrobial activity of the extract was tested after treated with several enzymes. Enzymes treated extract showed potent antimicrobial activity against B. subtilis and its activity was also retained for 5 h after trypsin treatments. Non-proteinaceous materials in the acidified extract also showed strong DNA-binding ability but did not show bacterial membrane permeabilizing ability. All our results indicate that mussel extract might contain the proteinaceous or non-proteinaceous antibacterial materials target not bacterial membrane but intracellular components. These results could be used to develop mussel extract as an additive for the improvement of stability or antimicrobial activity of antibiotics against specific bacteria.

• The Korean Journal of Mycology
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• v.26 no.4 s.87
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• pp.496-501
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• 1998

The mycelia of Tricholoma matsutake DGUM 26001, 26101, 26210 and FRI 91024 were used to determine the extracellular enzyme activity in mycelia. When the filtrate of culture broth after 30-day cultivation at $24^{\circ}C$ was used as a crude solution of extracellular enzyme, the average specific activity of ${\alpha}-amylase$ was 6142.3 unit/mg protein. The specific activity of xylanase was comparatively high. However, little or no enzyme activities were found for ${\beta}-glucosidase$, ligninase, CMCase, chitinase, protease, and lipase.

• Journal of Microbiology and Biotechnology
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• v.5 no.4
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• pp.206-212
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• 1995

A strain BL-29, which produces a extracellular lytic enzyme on E. coli was isolated from the soil. The strain was identified as belonging to the genus Bacillus sp. The lytic enzyme was purified to homogeneity by ion exchange chromatography and gel filtration. Specific activity of the purified enzyme was 28, 850 U/mg protein and yield of the enzyme was 5$%$. The purified enzyme showed a single band on SDS-PAGE and its molecular weight was estimated to be 31, 000 by SDS-polyacrylamide gel electrophoresis and gel filtration column chromatography. The optimum temperature and pH were $55^{\circ}C$ and pH 10.0, respectively. The enzyme was stable at $45^{\circ}C$ but enzyme activity was reduced by up to 50$%$ when the temperature was raised to $55^{\circ}C$ for 15 min. Stable range of pH was from 5.0 to 11.0. but Enzyme activity was inhibited by lead-acetate, mercuric chloride, ethylene glycol-bis-[$\beta$-aminoethyl ether]-N, N, $N^1, $N^1$-tetraacetic acid (EGTA), and ethylenediamine tetraacetic acid (EDTA), but not affected considerably by treatment with other chemical reagents.