• International Journal of Industrial Entomology and Biomaterials
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• 제9권1호
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• pp.29-33
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• 2004

Low molecular weight silk fibroin (LMSF), which was prepared by hydrolysis of silk fibroin using high-temperature and high-pressure method, was found to inhibit the oxidation of L-3,4,-dihydroxyphenylalanine (L-DOPA) catalyzed by mushroom tyrosinase (EC 1.14.18.1). LMSF contained mostly free amino acids such as L-glycine, L-alanine, and L-serine and oligopeptides, mainly glycine-alanine dimer. As a result of analyzing the inhibition kinetics from Lineweaver-Burk plots, L-glycine and glycine-alanine dimer showed noncompetitive behavior while uncompetitive behavior was observed in L-alanine, and L-serine. When weight percent concentration of ${ID_50}$ was compared, L-glycine was most effective on the inhibition and LMSF was also good enough for the inhibition effect of tyrosinase activity. LMSF showed a mixed-type inhibition and the inhibitory mechanism of LMSF might be caused by free amino acids and oligopeptides. As a result of spectroscopic observation with time, initial rate of increase of DOPAchrome decreased remarkably and the time to reach maximum absorbance increased as an increase of the concentration of L-glycine, meaning that L-glycine made itself mainly responsible for the formation of chelate with ${Cu^2+}$ in tyrosinase. However, in case of L-alanine, L-serine, and especially glycine-alanine dimmer, the production of DOPAchrome after an arrival at maximum absorbance decreased, indicating the production of adducts through the reaction with DOPAquinone.

• Journal of Microbiology and Biotechnology
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• 제27권4호
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• pp.768-774
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• 2017

Horseradish peroxidase (HRP) catalyzes the oxidation of aromatic compounds by hydrogen peroxide via insoluble polymer formation, which can be precipitated from the wastewater. For HRP immobilization, poly(lactic-co-glycolic acid) (PLGA) fine carrier supports were produced by using the Nano Spray Dryer B-90. Immobilized HRP was used to remove the persistent 2,4-dichlorophenol from model wastewater. Both extracted (9-16 U/g) and purified HRP (11-25 U/g) retained their activity to a high extent after crosslinking to the PLGA particles. The immobilized enzyme activity was substantially higher in both the acidic and the alkaline pH regions compared with the free enzyme. Optimally, 98% of the 2,4-dichlorophenol could be eliminated using immobilized HRP due to catalytic removal and partly to adsorption on the carrier supports. Immobilized enzyme kinetics for 2,4-dichlorophenol elimination was studied for the first time, and it could be concluded that competitive product inhibition took place.

• Journal of Plant Biology
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• 제38권1호
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• pp.11-18
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• 1995

Mercury-induced changes in Chl a fluorescence induction kinetics of scratched barley leaf segments were dependent on the presence of light. By the treatment of 50$\mu$M HgCl2 under light condition, Fm and Fp were decreased. However, they were not significantly reduced under dark condition even after 2 h of mercury treatment. Under dark condition the decrease in variable fluorescence (Fv) after P transient was blocked within 20 min of the treatment. The analysis of fast fluorescence rise curve suggests that the inhibitory site of mercury under both light and dark conditions is not at QB binding site and the inhibition does not involve the increase in inactive PSII centers. Under light condition the decrease in Fp was partially recovered by addition of 50 $\mu$M NH2OH. These results suggest that a major inhibitory site of mercury under dark condition is at the reducing side of PSII and the site under light condition is at the oxidizing side of PSII possibly in addition to the one under dark condition. Under both light and dark conditions, energy-dependent quenching(qE) was alomost completely repressed within 20 min of mercury treatment and noticible change in Fo was not observed. The qE repression is probably due to the blockage of transthylakoid ΔpH formation.

• 한국재료학회지
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• 제31권6호
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• pp.367-374
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• 2021

This paper presents the characteristics of gentamicin-loaded into cetyl trimethyl ammonium intercalated montmorillonite (GtM/CTMA/Mt) as a hybrid composite for a slow-released antibacterial delivery systems. The work describes the successful immobilization of gentamicin into the interlayers of surfactant-modified montmorillonite. Physicochemical characterization of the material is carried out by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy. The kinetics of the gentamicin release is investigated by in vitro study and analyzed based on UV-Vis spectrometry. In addition, antibacterial study is performed towards Klebsiella pneumoniae Staphylococcus aureus, Escherichia coli, and Streptococcus pyogenes. The results show that the gentamicin loading into CTMA/Mt increases the effectiveness of the antibacterial activity, as shown by the higher inhibition zone for all tested bacteria, compared to gentamicin as a positive control. The kinetics study suggests that the gentamicin release obeys the modified Korsmeyer-Peppas model. The physicochemical study and activity test demonstrate the feasibility of the GtM/CTMA/Mt for practical applications.

• 한국약용작물학회지
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• 제28권1호
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• pp.21-28
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• 2020

Background: Owing to its high efficiency in lipid and protein production, peanut (Arachis hypogaea L.) is considered one of most important crops world-wide. The kernels of peanuts are undoubtedly the most important product this plant, whereas the skin is almost completely neglected in nutraceutical terms. However, peanut skin contains potentially health-promoting phenolics and dietary fiber, and there is considerable potential for commercial exploitation. In this study, we evaluated the α-glucosidase inhibitory activity of an extract of peanut skin (PS). Methods and Results: The α-glucosidase inhibitory effects of 80% ethanol extracts of peanut (A. hypogaea L. 'Sinpalkwang') skin were evaluated and found to have a half-maximal inhibitory concentration (IC₅₀) value of 1.2 ㎍/㎖. Progress curves for enzyme reactions were recorded spectrophotometrically, and the inhibition kinetics revealed time-dependent inhibition with enzyme isomerization. Furthermore, using ultra-high performance liquid chromatography combined with quadrupole-orbitrap mass spectrometry, we identified 26 compounds in the peanut skin extract, namely, catechin, epicatechin, and 24 proanthocyanidins. Conclusions: The results suggest that peanut skin can be utilized as an effective source of α-glucosidase inhibition in functional foods and nutraceuticals.

• 대한화학회지
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• 제43권2호
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• pp.150-155
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• 1999

소량의 $CH_3Cl$ 기체를 첨가한 $C_2H_6-O_2-Ar$ 혼합 기체의 점화 지연 시간을 반사 충격파 이후의 온도가 1270∼1544 K인 범위에서 측정하였다. 실험 결과 $CH_3Cl$ 기체가 $C_2H_6$ 기체의 점화 과정을 지연시킴을 알 수 있었고, $CH_3Cl$ 기체의 농도가 증가함에 따라 점화 지연 시간이 증가함을 알 수 있었다. 그리고 $C_2H_6-CH_3Cl-O_2-Ar$ 혼합 기체에서 $CH_3Cl$ 기체의 점화 억제 효과를 반응 메카니즘 시각으로 살펴보기 위하여 컴퓨터를 이용한 모의 실험을 수행하였다.

• 한국식품과학회지
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• 제29권6호
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• pp.1269-1274
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• 1997

국내에서 재배된 Aloe vera에서 생리활성 물질인 acetylmannan을 분리 하고 그 제반의 특성을 규명하고 ACE저해효과 및 동력학적분석을 행한 결과 다음과 같은 결론을 얻었다. 알로에 베라 3.5 Kg으로 부터 에탄올에 불용성 다당체를 수득, 백색의 분말형태인 0.9 g의 acetylmannan을 얻었다. 분리한 acetylmannan은 탄수화물 67%를 함유하고 있으며 만노오즈는 60% 소량의 글루코오즈와 갈락토오즈로 이루어져 있고 아세틸기는 23%를 함유하고 있으며 acetyl group은 IR 스펙트럼에서 $1746\;cm^{-1}$, $1244\;cm^{-1}$ peak으로서 확인하였다. 과요오드 산화법에서 과요오드 음이온 소비량이 포름산 생성량에 비해 많고, 1, 4 글리코사이드 결합으로 이루어져 있음을 확인하였다. 또한 ACE에 대한 $IC_{-50}$ 값은 0.58 mM 이였으며, competitive 저해형식을 나타내었고. Ki 값은 0.068 mM 이였다.

• 약학회지
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• 제38권1호
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• pp.67-77
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• 1994

In order to investigate the feasibility of transmucosal delivery of the model peptide, LHRH, metabolism of LHRH and inhibition effect of medium chain fatty acid salts were studied in rabbit mucosal homogenate. LHRH incubated in homogenates of rectal(RE), nasal(NA) and vaginal(VA) mucosa were assayed by HPLC. Five to six degradation products of LHRH were deterted and the degradation of LHRH$(500\;{\mu}g/ml)$ followed the first order kinetics. The main degradation products were found as $LHRH^{1-5}(M-I)$, $LHRH^{1-3}(M-II)$ and $LHRH^{1-6}(M-III)$ by the method of amino acid analysis. The half-lives of LHRH in the mucosal homogenates were found to be less than 20 min at protein concentration of 2.5 mg/ml with the order of VA>NA>RE mucosal homogenate. Medium chain fatty acid salts such as sodium caprylate $(C_8)$, sodium caprate $(C_{10})$ and sodium laurate $(C_{12})$ at the concentration of $0.5%{\sim}1.0%$ inhibit the proteolysis of LHRH significantly. The addition of sodium laurate(0.5%) into the NA and VA mucosal homogenates protected LHRH completely from the degradation.

• 한국미생물·생명공학회지
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• 제21권4호
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• pp.342-347
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• 1993

It was proved that the cell growth followed a photo-inhibition model in light-limited turbidostat cultivation, having 1.06 (1/h) of maximum specific growth rate and 0.00094(kcal/$cm^2$/h) and 0.063 (kcal/$cm^2$/h) as half saturation and light inhibition constants, repectively. ${\beta}$-carotene production showed a growth related porcess. And the activation energy of Dunaliella salina was roughly estimated as 12.36 (kcal/mole) in employing Arrhenius relationship. It should also point out that relatively much porduction of ${\beta}$-carotene was observed at hight light intensity with yieding 1.04 (mg-carotene/g-dry cell/day) of specific product production rate while the cell growth was decreased. The optimal conditions of producing ${\beta}$-carotene in turbiodostat cultivation were as follows: $7.5{\times}10^{-3}$(kcal/$cm^2$/h)of light intensity, 2 (mM) and 50(mM) of nitrate and sodium bicarbonate concentrations and 100(ml/h) of $CO_2$ flow rate.

• Corrosion Science and Technology
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• 제4권1호
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• pp.8-14
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• 2005

The corrosion behaviour of mild steel in phosphoric acid solution in the presence and absence of pollutants viz. Chloride, Fluoride and Sulfate ions at 302K-333K was studied using mass loss and potentiostatic polarization methods. The addition of chloride and sulfate ions inhibits the mild steel corrosion in phosphoric acid while fluoride ions stimulate it. The effect of temperature on the corrosion behaviour of mild steel indicated that inhibition of chloride and sulfate ions decreased with increasing temperature. The adsorption of these ions (Chloride and sulfate) on the mild steel surface in acid has been found to obey Langmuir adsorption isotherm. The values of activation energy (Ea) and free energy of adsorption ($\Delta$) indicated physical adsorption of these ions (chloride and sulfate) on the mild steel surface. The plot of $logW_{f}$ against time (days) at 302K gives a straight line, which suggested that it obeys first order kinetics and also calculate the rate constant k and half-life time $t_{1/2}$.