• 공업화학
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• 제19권3호
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• pp.277-286
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• 2008

본 논문은 미생물 성장 공정에서의 기질 저해에 관한 modified Haldane 모델의 이론적 유도를 다룬다. 생물학적 개념인 기질-수용체 복합체의 작동 메커니즘을 바탕으로 새로운 미생물학적 동특성인 N-중첩된 다중 기질 저해 모델의 유도와 더불어 일반화가 이론적으로 고찰되었는데, 이것은 효소 반응에서의 단순 기질 저해 메커니즘이 자연스럽게 확장된 것이다. 결과적으로, 본 기질 저해에 관한 modified Haldane 모델은 완전저해 기질농도라는 생물학적 상수를 포함하고 있는, 잘 설계된 4-파라메터 동특성 모델임이 밝혀졌다.

• Journal of Microbiology and Biotechnology
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• 제13권3호
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• pp.332-337
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• 2003

Enzyme kinetics data play a vital role in the design of reactors and control of processes. In the present study, kinetic studies on pectinases were carried out. Partially purified polymethylgalacturonase (PMG) and polygalacturonase (PG) were the two pectinases studied. The plot of initial rate vs. initial substrate concentration did not follow the conventional Michaelis-Menten kinetics, but substrate inhibition was observed. For PMG, maximum rate was attained at an initial pectin concentration of 3 g/l, whereas maximum rate was attained when the initial substrate concentration of 2.5 g/l of polygalacturonic acid for PG I and PG II. The kinetic data were fitted to five different kinetic models to explain the substrate inhibition effect. Among the five models tested, the combined mechanism of protective diffusion limitation of both high and inhibitory substrate concentrations (semi-empirical model) explained the inhibition data with 96-99% confidence interval.

• KSBB Journal
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• 제13권6호
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• pp.730-734
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• 1998

An이ew식과 Aiba삭을 조합하여 에탄올 생산단주인 Saccharomyces cerevisiae ATCC 24858의 비성장속도를 당농도와 에탄올 농도의 함수로 표현하였다. 기침의 저해영향을 받지 않는 최대 당농도 $S_m$은 150 g/L이며 기질의 저해영향은 기질농도 S와 $S-S_{max}$항의 함수로 표현되었다. 최대 비성장 속도 ${\mu}max 는 0.49 hr^{-1}, Monod상수 K_s$는 19 g/L, Andrew식의 기질저해상수 $K_1$는 139 g/L이였다. 또한 비성장속도에 영향을 마치지 앓는 최대알콜농도 Pm이 존재하였으며 그 값은 2 g/L 이였다. 따라서 Aiba식에서 비성장속도에 영향을 미치는 에탄올 농도항은 P-Pm으보 표현되었다. 본 연구의 알코올생산균주에 대한 비성장속도의 완성된 수식은 디음과 같으며 이 수식에 위한 계산값은 평균오차 6% 내외의 범위에서 실험값과 일치하였다.

• 한국물환경학회지
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• 제33권1호
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• pp.8-14
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• 2017

Microcystis aeruginosa (M. aeruginosa) is a cyanobacterium species that can form harmful algal blooms in freshwater bodies worldwide. The use of pine needle extract (PNE) to control nuisance algae by allelopathic inhibition will be environmentally friendly and promising. PNE removed successfully upto 98% of M. aeruginosa at the following optimal conditions: pH 7, $25^{\circ}C$ of temperature, 100 rpm of mixing rate, 5 min of mixing time. These results was indicated that the amount of 1 g/L PNE was removed 1g dryweight/L of M. aeruginosa. The kinetic data showed substrate inhibition kinetics and maximum growth rate was obtained when the M. aeruginosa was grown in medium containing 0.5 g/L of initial concentration of PNE. Different substrate inhibition models were fitted to the kinetic data and found the Luong model was best. The model predicted kinetic parameters were in agreement with the experimental findings. The natural extract, PNE, can be a promising inhibition due to its high efficiency and low dose requirements.

• Journal of Microbiology and Biotechnology
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• 제24권7호
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• pp.954-958
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• 2014

Succinic semialdehyde dehydrogenase (SSADH) catalyzes the oxidation of succinic semialdehyde (SSA) into succinic acid in the final step of ${\gamma}$-aminobutyric acid degradation. Here, we characterized Bacillus subtilis SSADH (BsSSADH) regarding its cofactor discrimination and substrate inhibition. BsSSADH showed similar values of the catalytic efficiency ($k_{ca}t/K_m$) in both $NAD^+$ and $NADP^+$ as cofactors, and exhibited complete uncompetitive substrate inhibition at higher SSA concentrations. Further analyses of the sequence alignment and homology modeling indicated that the residues of catalytic and cofactor-binding sites in other SSADHs were highly conserved in BsSSADH.

• Journal of Microbiology
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• 제35권3호
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• pp.193-199
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• 1997

From several industrial wastewaters, 14 bacterial strains which degrade benzene, toluene, o-xylene, m-xylene, or p-xylene (BTX) were obtained. These strains were characterized as to their species composition and the substrate range, kinetic parameters and the substrate interactions were investigated. Although BTX components have a similar chemical structure, isolated strains showed different substrate ranges and kinetic parameters. None of the strains could degrade all of BTX components and most of them showed an inhibition (Haldane) kinetics on BTX, BTX mixtures were removed under inhibitory substrate interactions with variation in the intensity of inhibition. For a complete degradation of BTX, a defined mixed culture containing three different types of patyways was constructed and all of the BTX components were simultaneously degraded with the totla removal rate of 225.69 mg/g biomass/h Judging from the results, the obtained mixed culture seems to be useful for the treatment of BTX-contaminated wastewater or groundwater as well as for the removal of BTX from the contaminated air stream.

• BMB Reports
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• 제30권5호
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• pp.332-336
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• 1997

The stimulatory effects of leucine on the activities of two soluble forms of brain glutamate dehydrogenase isoproteins (GDH I and GDH II) have been studied at various conditions. There were significant differences between GDH I and GDH II in their sensitivities to the action of leucine. When the effects of varied leucine concentrations on GDH activities were studied in the direction of reductive amination of 2-oxoglutarate with NADPH as a coenzyme, a marked activation was observed for both isoproteins at leucine concentrations up to 10 mM, whereas both isoproteins showed activation to a lesser extent with NADH as a coenzyme. The stimulatory effects of leucine on GDH activities in the direction of the oxidative deamination of glutamate were also observed, but to a much lesser extent. Leucine relieved the inhibition of GDH I by GTP and this resulted in an increase in the apparent activation by leucine in the presence of GTP. 2-Oxoglutarate was found to give rise to high substrate inhibition and leucine significantly reduced the substrate inhibition in the presence of $200\;{\mu}M$ NADH. Thus, the effects of leucine might be composed of a direct effect on the enzyme together with a relief of high substrate inhibition.

• 한국환경과학회지
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• 제17권12호
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• pp.1325-1330
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• 2008

This study was carried out with the detection for multiresidue of the carbamate pesticide such as carbaryl and cabofuran by enzyme-inhibition method. The check time for determination of acetylcholinesterase(AChE) activity was selected at 60 sec. The AChE activity in chicken brain determined by the Ellman's method was $162{\mu}$mol/min/g protein. $I_{50}$ for AChE by carbamate pesticide with wet kit was 0.169mg/L of carbaryl and 0.089mg/L of cabofuran, respectively. The incubation time for enzyme kit with substrate kit was 30min for determination of AChE activity. Enzyme kit with substrate kit was stable at $4^{\circ}C\;and\;25^{\circ}C$ for 5 days. Limit detection concentration of carbaryl with dry kit for AChE was 0.05mg/L. The dry kit such as wet kit applied Enzyme-Inhibition(EI) method with AChE was confirmed the multi residue method to detect the carbamate pesticides.

• Bulletin of the Korean Chemical Society
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• 제32권4호
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• pp.1241-1248
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• 2011

Three dimensional quantitative structure-activity relationships (3D-QSARs) between new thiosemicarbazone analogues (1-31) as a substrate molecule and their inhibitory activity against tyrosinase as a receptor were performed and discussed quantitatively using CoMFA (comparative molecular field analysis) and CoMSIA (comparative molecular similarity indices analysis) methods. According to the optimized CoMSIA 2 model obtained from the above procedure, inhibitory activities were mainly dependent upon H-bond acceptor favored field (36.5%) of substrate molecules. The optimized CoMSIA 2 model, with the sensitivity of the perturbation and the prediction, produced by a progressive scrambling analysis was not dependent on chance correlation. From molecular docking studies, it is supposed that the inhibitory activation of the substrate molecules against tyrosinase (PDB code: 1WX2) would not take place via uncompetitive inhibition forming a chelate between copper atoms in the active site of tyrosinase and thiosemicarbazone moieties of the substrate molecules, but via competitive inhibition based on H-bonding.

• Journal of Microbiology and Biotechnology
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• 제1권3호
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• pp.182-187
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• 1991

The effects of acrylonitrile and acrylamide on the enzyme action of nitrile hydratase of Brevibacterium sp. CH1 and CH2 strains used for the biotransformations of nitriles were studied. The excessive substrate (acrylonitrile) and product (acrylamide) inhibited the enzyme activity competitively. In comparison with 0.2 mol/l of CH1 strain, the substrate inhibition of CH2 strain began to appear only at a high acrylonitrile concentration of 0.91 mol/l. In a packed bed reactor, dispersed plug flow model was proposed and this model was proved to be valid by the experiment. Also acrylamide productivity decreased sharply when acrylamide concentration in the substrate solution exceeded 20％ (wt/v).