• Journal of Microbiology and Biotechnology
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• 제15권1호
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• pp.125-130
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• 2005

The growth and phosphatase (phosphomonoesterase) activity of Chroococcidiopsis culture isolated from the cryptoendoliths of the Antarctic were compared with a similar isolate from the Arizona hot desert. Such cyanobacteria living inside rocks share several features with the immobilized cells produced in the laboratory. This study has relevance because the availability of phosphorus is a key factor influencing the growth of these cyanobacteria in nature, in such unique ecological niches as the hot and cold deserts. Phosphatase activity therefore is of particular importance for these organisms if they are to survive without any other source of phosphorus availability. Also, there is paucity of knowledge regarding this aspect of study in cyanobacterial cultures from these extreme environments. The salient feature of this study shows the importance of specific pH and temperatures for growth and phosphatase activity of both cultures, although there were marked differences between the two isolates. The pH and temperature optima for growth and phosphatase activity (PMEase) of Chroococcidiopsis 1 and 2 were 9.5, $240^{\circ}C$ and 8.5, $40^{\circ}C$ respectively. The $K_m and V_max$ values of cultured Chroococcidiopsis 1 showed lower affinity of PMEase for the substrate compared to the enzyme affinity of the same organism when found within the rocks; Chroococcidiopsis 2 and Arizona rocks containing the same alga however showed similar affinity of PMEase for the substrate. An interesting observation was the similarity in response of immobilized Chroococcidiopsis 1 culture and the same organism in the Antarctic rocks to low light and low temperature stimulation of PMEase. This thermal response seems to be related to the ability of the immobilized Antarctic isolate and the rocks to either cryoprotect the PMEase or undergo a change to save the enzyme from becoming nonfunctional under low temperatures. The free cells of Chroococcidiopsis 1 culture however did not show such responses.

• Journal of Microbiology and Biotechnology
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• 제28권9호
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• pp.1447-1456
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• 2018

The amylosucrase encoding gene from Deinococcus geothermalis DSM 11300 (DgAS) was codon-optimized and expressed in Escherichia coli. The enzyme was employed for biosynthesis of three different dihydroxybenzene glucosides using sucrose as the source of glucose moiety. The reaction parameters, including temperature, pH, and donor (sucrose) and acceptor substrate concentrations, were optimized to increase the production yield. This study demonstrates the highest ever reported molar yield of hydroquinone glucosides 325.6 mM (88.6 g/l), resorcinol glucosides 130.2 mM (35.4 g/l) and catechol glucosides 284.4 mM (77.4 g/l) when 400 mM hydroquinone, 200 mM resorcinol and 300 mM catechol, respectively, were used as an acceptor substrate. Furthermore, the use of commercially available amyloglucosidase at the end of the transglycosylation reaction minimized the gluco-oligosaccharides, thereby enhancing the target productivity of mono-glucosides. Moreover, the immobilized DgAS on Amicogen LKZ118 beads led to a 278.4 mM (75.8 g/l), 108.8 mM (29.6 g/l) and 211.2 mM (57.5 g/l) final concentration of mono-glycosylated product of hydroquinone, catechol and resorcinol at 35 cycles, respectively, when the same substrate concentration was used as mentioned above. The percent yield of the total glycosides of hydroquinone and catechol varied from 85% to 90% during 35 cycles of reactions in an immobilized system, however, in case of resorcinol the yield was in between 65% to 70%. The immobilized DgAS enhanced the efficiency of the glycosylation reaction and is therefore considered effective for industrial application.

• Environmental Analysis Health and Toxicology
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• 제23권1호
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• pp.17-22
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• 2008

A rapid, inexpensive enzymatic method is proposed for indirect water quality testing in terms of heavy metal toxicity. The activity of glucose-6-phosphate dehydrogenase was applied for heavy metal toxicity test as an effective criterion in water quality. The toxicity of Pb (lead) and Cd (cadmium) for water flea, Moina macrocopa, were evaluated for $2{\sim}8\;days$ with variables of mobilization ability. And the reproduction impairment of Moina macrocopa were investigated as the parameter of chronic toxicity twst for Pb and Cd. As a result, the $EC_{50}$ for immobilization of Moina macrocopa were Pb and Cd were 1.6749 and 0.4683, respectively. The values of reproducive impairment to Moina macrocopa for Pb and Cd were 9.5938 and 8.3264 in $EC_{50}$. A significant alteration of G6PDH (Glucose-6-phosphate dehydrogenase) activity of Moina macrocopa was observed when Cd and Pb were treated in media. The results obtained indicate that G6PDH activity of Moina macrocopa can be used as an indicative parameter in aquatic toxicity tests for heavy metals.

• Bulletin of the Korean Chemical Society
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• 제25권8호
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• pp.1195-1201
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• 2004

Tyrosinase was covalently immobilized on platinum electrode according to the method we developed for laccase (Bull. Korean Chem. Soc. 2002, 23(7), 385) and p-chlorophenol, p-cresol, and phenol could be detected with sensitivities of 334, 139 and 122 nA/ ${\mu}M$ and the detection limits of 1.0, 2.0, and 2.5 ${\mu}M$, respectively. The response time ($t_{90\%}$) is 3 seconds for p-chlorophenol, and 5 seconds for p-cresol and phenol. The optimal pHs of the sensor are in the range of 5.0- 6.0. This sensor can tolerate at least 500 times repeated injections of p-chlorophenol with retaining 80% of initial activity. In case of tyrosinase and laccase co immobilized platinum electrode, the sensitivities are 560 nA/ ${\mu}M$ for p-phenylenediamine (PPD) and 195 nA/ ${\mu}M$ for p-chlorophenol, respectively. The sensitivity of the bi-enzyme sensor for PPD increases 70% compared to that of only laccase immobilized one, but the sensitivity for p-chlorophenol decreases 40% compared to that of only tyrosinase immobilized one. The sensitivity increase for the bi-enzyme sensor for PPD can be ascribed to the additional catalytic function of the co-immobilized tyrosinase. The sensitivity decrease for p-chlorophenol can be explained by the “blocking effect” of the co-immobilized laccase, which hinders the mass transport through the immobilized layer. If PPD was detected with the electrode that had been used for p-chlorophenol, the sensitivity decreased 20% compared to that of the electrode that had been used only for PPD. Similarly, if p-chlorophenol was detected with PPD detected electrode, the sensitivity also decreased 20%. The substrate-induced conformation changes of the enzymes in a confined layer may be responsible for the phenomena.

• 한국식품과학회지
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• 제11권3호
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• pp.192-199
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• 1979

비교적 높은 역가의 포도당 이성화 효소를 생산하는 방사선균을 토양에서 선별하여 이성화 효소의 세포 고정화를 행하였다. 특히 최종 제품(pellet form)의 물리적 견고성을 얻기 위하여 세포를 $65^{\circ}C$로 15분간 열처리하고 선택적 건조를 행하여 얻은 세포 slurry를 가용성 전분과 섞은 후 사출시켜 pellet form으로 만들었다. 5% glutaraldehyde를 가교제로서 pellet 균괴를 3시간 처리함으로 효소의 세포 고정화를 이룩하였다. 최종 제품은 물리적 견고성이 양호하였고 효소의 회수율은 26%였으며 비활성도는 건물 g당 48.1 단위였다. 세포 고정화시킨 이성화 효소는 가용성 효소와 매우 유사한 효소학적 성질을 보여 주었다. 즉 최적 pH ; $7.5{\sim}9.0$, 최적 온도 ; $80{\sim}85^{\circ}C$, 활성화 에너지 ; 10.9 kcal/mole, 포도당에 대한 $K_m$값 ; 10.9 M이었다. 고정화 효소는 열안정과 pH 안정성이 양호함을 보여주었다.

• 생명과학회지
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• 제26권5호
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• pp.603-607
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• 2016

유기용매 내성 세균 Pseudomonas sp. BCNU 106으로부터 생산된 리파아제 조효소액은 pH 4-10의 넓은 범위의 pH와 37℃에서 매우 안정적이었다. BCNU 106의 리파아제 안정성은 25% xylene, hexane, octane, toluene, chloroform 및 dodecane에서 증가하였으며, 상업적인 고정화 효소와 비교해도 우수한 안정성을 보이고 있다. 그리고 Cu²⁺, Hg²⁺, Zn²⁺ 및 Mn²⁺ 존재 하에서 110% 이상의 상대활성을 나타낸 반면에, Fe²⁺에서는 효소활성이 억제되었다. 게다가 계면활성제인 tween 80과 triton X-100 및 SDS에서도 높은 안정성을 유지됨이 확인되었다. 본 연구에서 유기용매 내성 Pseudomonas sp. BCNU 106의 리파아제는 고정화 효소에 못지않은 효소 활성 및 안정성을 유지함이 밝혀져 다양한 산업공정에서 잠재적인 생물촉매로 적용될 수 있는 가능성을 확인할 수 있었다.

• Journal of Ginseng Research
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• 제37권3호
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• pp.315-323
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• 2013

Ginseng is known to have antistress effects. Previously, red ginseng (RG) was shown to repress stress-induced peptidyl arginine deiminase type IV (PADI4) via estrogen receptor ${\beta}$ ($ER{\beta}$) in the brain, thus inhibiting brain cell apoptosis. Moreover, tumor necrosis factor (TNF)-${\alpha}$ plays a critical role in immobilization (IMO) stress. However, the signaling pathway of RG-mediated repressesion of inflammation is not completely understood. In this study, we determined how RG modulated gene expression in stressed brain cells. Since secretion of TNF-${\alpha}$ is modulated via TNF-${\alpha}$ converting enzyme (TACE) and nuclear factor (NF)-${\kappa}B$, we examined the inflammatory pathway in stressed brain cells. Immunohistochemistry revealed that TACE was induced by IMO stress, but RG repressed TACE induction. Moreover, PADI4 siRNA repressed TACE expression compared to the mock transfected control suggesting that PADI4 was required for TACE expression. A reporter assay also revealed that $H_2O_2$ oxidative stress induced NF-${\kappa}B$ in neuroblastoma SK-N-SH cells, however, RG pretreatment repressed NF-${\kappa}B$ induction. These findings were supported by significant induction of nitric oxide and reactive oxygen species (ROS) by oxidative stress, which could be repressed by RG administration. Taken together, RG appeared to repress stress-induced PADI4 via TACE and NF-${\kappa}B$ in brain cells thus preventing production of ROS and subsequently protecting brain cells from apoptosis.

• 대한화학회지
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• 제45권3호
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• pp.223-229
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• 2001

흐름주입 장치를 이용하여 화학발광법에 의한 전혈 중의 당을 정량하는 방법에 대하여 연구하였다. 당의 효소반응에서 생성되는 과산화수소에 의하여 424nm에서 발생하는 luminol의 화학발광 세기의 차이를 정량에 이용하였다. 효소반응기는 glucose oxidase를 aminopropyl glass bead에 혼입하여 만들었으며, 흐름셀에서 발생하는 화학발광의 세기는 광섬유 다발을 이용하여 측정하였다. 최적 실험조건을 구하기 위하여 화학발광 시약 및 효소반응기의 pH, 흐름속도 및 온도가 화학발광세기에 미치는 영향을 조사하였다. 최적실험조건에서 구한 검정 곡선은 $1.0{\times}10^{-1}$~ 7.0mM에서 직선성이 성립하였으며, 검출한계는 $6.0{\times}10^{-2}$mM이었다. 본 방법을 전혈 중의 당 정량에 적용하였으며, 그 결과를 기존의 분석법에서 구한 결과와 비교하였다. 또한, 회수율 측정을 통하여 본 방법의 신뢰성을 검증하였다.

• 한국미생물·생명공학회지
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• 제48권1호
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• pp.12-23
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• 2020

Edible films containing antimicrobial agents can be used as safe alternatives to preserve food products. Essential oils are well-recognized antimicrobials. However, their low water solubility, volatility and high sensitivity to oxygen and light limit their application in food preservation. These limitations could be overcome by embedding these essential oils in complexed product matrices exploiting the encapsulation efficiency of β-cyclodextrin. This study focused on the maximization of β-cyclodextrin production using cyclodextrin glucanotransferase (CGTase) and the evaluation of its encapsulation efficacy to fabricate edible antimicrobial films. Response surface methodology (RSM) was used to optimize CGTase production by Brevibacillus brevis AMI-2 isolated from mangrove sediments. This enzyme was partially purified using a starch adsorption method and entrapped in calcium alginate. Cyclodextrin produced by the immobilized enzyme was then confirmed using high performance thin layer chromatography, and its encapsulation efficiency was investigated. The clove oil/β-cyclodextrin inclusion complexes were prepared using the coprecipitation method, and incorporated into chitosan films, and subjected to antimicrobial testing. Results revealed that β-cyclodextrin was produced as a major product of the enzymatic reaction. In addition, the incorporation of clove oil/β-cyclodextrin inclusion complexes significantly increased the antimicrobial activity of chitosan films against Staphylococcus aureus, Staphylococcus epidermidis, Salmonella Typhimurium, Escherichia coli, and Candida albicans. In conclusion, B. brevis AMI-2 is a promising source for CGTase to synthesize β-cyclodextrin with considerable encapsulation efficiency. Further, the obtained results suggest that chitosan films containing clove oils encapsulated in β-cyclodextrin could serve as edible antimicrobial food-packaging materials to combat microbial contamination.

• KSBB Journal
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• 제15권1호
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• pp.42-48
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• 2000

본 연구에서는 고정화 UK를 이용한 융합단백질의 절단방응에 대해 UK의 고정화, 고정화 UK의 특성과 절단방응, 절단반응 후의 분리정제 그리고 고정화 UK으 재생에 대해 실험하였다. 고정화 수율은 99% 이상이였고 고정화 후의 효소활성은 80%를 유지하였다. 융합단백질 전단반응에서 액상 UK와 고정화 UK를 이용한 회분식 반응 모두 약 70%의 절단반응을 얻었고, 특히 고정화 UK의 사용시 부반응이 매우 낮은 이점이 있었다. 컬럼식 절단반응에서는 기절의 주입속도에 따라 절단수율은 크게 변화하였다. 최적의 유속은 50%의 절단수율을 얻은 1 bed volume/h로 설정하였다. 고정화 효소반응의 이점인 안정성과 반복사용 측면에서는 액상 UK 대비 고정화 UK가 높은 열안정성을 보였고 낮은 pH에서는 10% 이상 높은 활성을 유지하였다. 반복사용을 위해 6M GuHCl을 사용하여 인위적으로 풀림, 재접힘을 한 경우 98%의 활성을 얻음으로 타당성이 있음을 제시하였다. 또한 목적 단백질의 분리를 위하여 산침전 후 expanded bed adsorption 크로마토그래피를 이용함으로써 연속화된 고수율의 정제공정을 가능하게 하였다. 이러한 고정화 UK를 이용한 절단방응 및 정제시스템을 구축함으로써 융합단백지의 생산공정에 매우 유용하게 사용될 것으로 생각되어진다.