• Journal of Applied Biological Chemistry
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• 제59권1호
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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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• 제19권5호
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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.

• 한국식품영양학회지
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• 제16권2호
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• pp.152-157
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• 2003

Serratia marcescen ATCC 25419 protease를 ammonium sulfate treatment, DEAE-cellulose anion exchange chromatography등의 방법으로 정제하였는데 최종 단계에서 667.5 unit/mg 이었으며 회수율은 43%이었고 448배 정제되었다. 정제한 S. marcescens protease로부터 아포효소를 만든 후 금속 재활성화에 대해 조사하였다. S. marcescens protease는 EDTA에 의해 완전히 활성을 잃는 metalloenzyme이며 Hg, Fe, Cu 등에 의해서 효소 활성을 70% 이상 잃은 반면, Co는 효소 활성을 약 20% 정도 증가시켰다. 아포효소의 재활성화는 pH 6~8에서 Mn, Co, Zn 등이 효과적이었다. Mn, Co, Zn등을 아포효소에 가하여 만든 효소들 중에서 Zn-효소는 효소 활성도, 알칼리-불활성화, 열-안정성 면에서 원래 protease와 유사하였다.

• Journal of Microbiology
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• 제44권3호
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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.

• 약학회지
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• 제41권6호
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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.

• 한국미생물·생명공학회지
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• 제23권5호
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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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• 제42권4호
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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.

• 한국수산과학회지
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• 제54권3호
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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.

• 한국균학회지
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• 제26권4호통권87호
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• pp.496-501
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• 1998

송이균사(Tricholoma matsutake DGUM 26001, DGUM 26101, DGUM 26210, FRI 91024)를 사용하여 균사의 효소활성을 측정하였다. $24^{\circ}C$에서 30일간 배양후 그 여액을 조효소 용액으로 사용하였을 때, ${\alpha}-amylase$ 효소의 평균 비활성은 6142.3 unit/mg protein이었다. 배양여액 중의 xylanase의 세포의 효소활성은 상대적으로 높았으나, ${\beta}-glucosidase$, ligninase, CMCase, chitinase, pretense및 lipase의 효소활성은 낮거나 거의 없었다.

• Journal of Microbiology and Biotechnology
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• 제5권4호
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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.