• Preventive Nutrition and Food Science
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• 제3권1호
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• pp.36-42
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• 1998

Ion-selective eleltrodes(ISEs) are simple electrodechemical devices for the direct measurement of ions in the samples. A novel potentiometric biosensor for the determination of L-Malate or D-isocitrate has been developed by using CO2-3 -ISE-FIA system was composed of a pump, an injector, a malic enzyme or isocitric dehydrogenase enzyme reactor, a CO2-3 -ISE, a pH/mV meter, and an integrater. The various factors, such as buffer capacity types of plstericizer and polymer, were optimized for the CO2-3 selectivity. In this novel CO2-3 --ISE-FIA system, the potential difference due to the amount of CO2-3 produced from each enzyme reaction was proportional to the amount of L-malate or D-isocitrate.

• Journal of Microbiology and Biotechnology
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• 제11권5호
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• pp.763-771
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• 2001

Biphenyl dioxygenase (BPDO), which catalyzes the first step in the bacterial degradation of biphenyl and polychlorinated biphenyls, was characterized in Pseudomonas sp. B4. The bphA locus containing the four structural genes encoding BPDO were cloned and sequenced. A regulatory gene as well as a putative regulatory sequence were identified upstream of this locus. A transposase-like gene was found within a 1-kb region further upstream, thereby suggesting that the bphA locus may be carried on a transposable element. The three components of the BPDO enzyme have been separately overexpressed and purified from E. coli. The ferredoxin and terminal dioxygenase components showed biochemical properties comparable to those of two previously characterized BPDOs, whereas the ferredoxin reductase exhibited an unusually high lability. The substrate selectivity of BPDO was examined in vivo using resting cell assays performed with mixtures of selected polychlorinated biphenyls. The results indicated that para-substituted congeners were the preferred substrates. In vitro studies were carried out on a BPDO complex where the reductase from strain B4 we replaced by the more stable isoform from Comamonas testosteroni B-356. The BPDO enzyme had a specific activity of $0.26{\pm}0.02 {\mu}mol {min^-1}{mg^-1}\;of\;ISP_{BPH}$ with biphenyl as the substrate. The 2,3-, 4,4'-, and 2,4,4'-chlorobiphenyls were converted to single dihydrodiols, while 2,4'-dichlorobiphenyl gave rise to two dihydrodiols. The current data also indicated that 2,4,4'-trichlorobiphenyl was a better substrate than the 4,4'-dichlorinated congener.

• BMB Reports
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• 제44권2호
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• pp.87-95
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• 2011

Enzymatic catalysis has been pursued extensively in a wide range of important chemical processes for their unparalleled selectivity and mild reaction conditions. However, enzymes are usually costly and easy to inactivate in their free forms. Immobilization is the key to optimizing the in-service performance of an enzyme in industrial processes, particularly in the field of non-aqueous phase catalysis. Since the immobilization process for enzymes will inevitably result in some loss of activity, improving the activity retention of the immobilized enzyme is critical. To some extent, the performance of an immobilized enzyme is mainly governed by the supports used for immobilization, thus it is important to fully understand the properties of supporting materials and immobilization processes. In recent years, there has been growing concern in using polymeric materials as supports for their good mechanical and easily adjustable properties. Furthermore, a great many work has been done in order to improve the activity retention and stabilities of immobilized enzymes. Some introduce a spacer arm onto the support surface to improve the enzyme mobility. The support surface is also modified towards biocompatibility to reduce non-biospecific interactions between the enzyme and support. Besides, natural materials can be used directly as supporting materials owning to their inert and biocompatible properties. This review is focused on recent advances in using polymeric materials as hosts for lipase immobilization by two different methods, surface attachment and encapsulation. Polymeric materials of different forms, such as particles, membranes and nanofibers, are discussed in detail. The prospective applications of immobilized enzymes, especially the enzyme-immobilized membrane bioreactors (EMBR) are also discussed.

• 펄프종이기술
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• 제31권2호
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• pp.8-14
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• 1999

A screening has been performed to find hyper-ligninolytic fungi, which degtrade beech and pine lignin extensively in order to broaden the understanding of the ligninolytic enzymes elaborated by various white-rot fungi. One hundred and twenty two ligninolytic strains were selected from decayed woods with a selective medium for screening ligninolytic wood-rotting fungi. Two of them, Phanerochaete sordida YK-624 and YK-472, showed much higher ligninolytic activity and selectivity in beech-wood degradation than typical lignin-degrading fungi, phanerochaete chrysosporium and Coriolus versicolor. They also degraded birch dioxane lignin and residual lignin in unbleached kraft pulp(UKP) much more extensively than P. chrysosporium and C. versicolor. During fungal treatment of beech wood-powder, the fungus strain P. sordida YK-624 showed higher activity of extracellular manganese peroxidase (MnP) in the medium than P. chrysosporium. It also showed MnP activity, which would not be lignin peroxidast during treatment of oxygen-bleached kraft pulp(OKP) and under enzyme-inducing conditin.

• Journal of Electrochemical Science and Technology
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• 제4권1호
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• pp.41-45
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• 2013

Platinum is a well known element which shows a significant electrocatalytic activity in many important applications. In glucose sensor, because of the poisoning effect of reaction intermediates and the low surface area, the electrocatalytic activity towards the glucose oxidation is low which cause the low sensitivity. So, we fabricate a nanoporous PtZn alloy electrode by deposition-dissolution method. It provides a high active surface and a large enzyme encapsulating space per unit area when it used for an enzymatic glucose sensor. Glucose oxidase was immobilized on the electrode surface by capping with PEDOT composite and PPDA. The composite and PPDA also can exclude the interference ion such as ascorbic acid and uric acid to improve the selectivity. The surface area was determined by cyclic voltametry method and the surface structure and the element were analyzed by Scanning Electron Microscope (SEM) and Energy Dispersive X-ray spectroscopy (EDX), respectively. The sensitivity is $13.5{\mu}A/mM\;cm^2$. It is a remarkable value with such simply prepared senor has high selectivity.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2001년도 추계학술발표대회
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• pp.652-655
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• 2001

The comparative study of enzymes that catalyze a similar reactions but have different substrate spectrum and/or stereospecificity is a powerful approach to understanding the reaction mechanism between the relative enzymes, and it was also an useful tool to cloning the related enzyme, without the typical cloning from DNA library of genomic pools. For this purpose, we conducted an approach that the comparison at the molecular and protein level of esterases, from various sources including a previously identified (S)-stereospecific esterase of Pseudomonas sp. ES1. As expected, we found an esterase family genes that shared a high similarity at the protein and genetic level in the identical genus Pseudomonad. The striking structural and biochemical identity strongly suggested the family genes to be an identical one. We, hence, aligned the family genes and designated a degenerated primer for PCR-cloning using six Pseudomonas strains as templates. As a result, a recombinant esterase from Pseudomonas fluorescens KCTC 1767 was cloned and high-level expressed with high selectivity to (R,S)-ketoprofen ethyl ester. The enzyme exhibited a high ester-hydrolyzing activity to (S)-ketoprofen but did not hydrolyzed the opposite stereoisomer. Further characteristics were discussed in our presentation.

• 공업화학
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• 제25권2호
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• pp.152-156
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• 2014

Isoquercitrin (IQ)은 폴리페놀의 일종인 quercetin (QU)의 3번 위치에 glucose가 하나 결합해 있는 배당체로서, 천연에는 미량만이 존재하고 있다. 최근 QU의 2배당체인 rutin (RU)을 기질로 사용하여 효소에 의한 부분 가수분해에 의해 IQ를 합성할 수 있다는 것이 알려졌다. 본 논문에서는, $Pecinex^{TM}$ 계열의 복합 효소를 사용하여 RU의 선택적 가수분해에 의해 IQ를 합성하는 반응에서 최적 효소를 선정하고, 효소량 및 반응물의 농도 등의 변수에 따른 반응성을 검토하였다. 그 결과, $50^{\circ}C$에서 1%의 반응물 농도로 RU 1 g 대비 8 mL의 Ultra Clear를 사용하는 것이 반응 속도 및 IQ의 선택성 측면에서 최적인 것으로 나타났다.

• 대한화학회지
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• 제43권3호
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• pp.271-279
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• 1999

과산화수소의 정량을 위하여 닭의 소장조직과 ferrocene을 탄소반죽에 혼입시켜 만든 효소전극의 전기화학적 특성을 조사하였다. 조사된 전극은 t100%=3sec의 빠른 감응시간과 5.0X10-5 M(S/N=3)의 검출한계를 보여 주었으며, 방해 물질들에 대하여 좋은 선택성을 보 여 주었다. 또한 다른 동식물 조직을 이용하여 만든 센서와 비교할 때, 검정곡선이 좋은 직선성을 보여 주었으며 생촉매 안정성이 좋았고 보다 큰 감응신호를 보여 주었다.

• Interdisciplinary Bio Central
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• 제5권2호
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• pp.3.1-3.7
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• 2013

Recently, the productivity of drug discovery has gradually decreased as the limitations of single-target-based drugs for various and complex diseases become exposed. To overcome these limitations, drug combinations have been proposed, and great efforts have been made to predict efficacious drug combinations by statistical methods using drug databases. However, previous methods which did not take into account biological networks are insufficient for elaborate predictions. Also, increased evidences to support the fact that drug effects are closely related to metabolic enzymes suggested the possibility for a new approach to the study drug combinations. Therefore, in this paper we suggest a novel approach for analyzing drug combinations using a metabolic network in a systematic manner. The influence of a drug on the metabolic network is described using the distance between the drug target and an enzyme. Target-enzyme distances are converted into influence scores, and from these scores we calculated the correlations between drugs. The result shows that the influence score derived from the targetenzyme distance reflects the mechanism of drug action onto the metabolic network properly. In an analysis of the correlation score distribution, efficacious drug combinations tended to have low correlation scores, and this tendency corresponded to the known properties of the drug combinations. These facts suggest that our approach is useful for prediction drug combinations with an advanced understanding of drug mechanisms.

• 공업화학
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• 제23권4호
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• pp.394-398
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• 2012

아스트라갈린(AS)은 폴리페놀의 일종인 캠페롤(KR)에 글루코스가 하나 결합해있는 배당체로서, 천연에는 미량만이 존재하고 있다. 최근 tea seed extract (TSE)에 포함되어 있는 camelliaside A (CamA) 및 camelliaside B (CamB)로부터 복합효소인 Mash에 의한 부분가수분해에 의해 AS를 합성할 수 있다는 것이 알려졌다. 본 논문에서는, Mash에 의한 TSE의 선택적 가수분해에 의해 AS를 제조하는 공정에서 반응 온도, 효소량 및 반응물의 농도 등의 변수에 따른 반응성을 검토하였다. 반응 온도, 효소량 등이 증가할수록 AS의 생성 반응은 빨랐으나, 일단 생성된 AS가 급격하게 KR로 변환되는 문제점이 나타났다. 결론적으로, 반응 속도 및 AS의 선택성 측면을 고려하면, $50^{\circ}C$에서 TSE 대비 2배의 Mash를 사용하여 15%의 기질 농도에서 반응을 수행하는 것이 최적인 것으로 나타났다.