• Journal of Life Science
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• v.9 no.1
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• pp.99-105
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• 1999

The aims of this studies were carried out to investigate the antioxidant activity on low density lipoprotein(LDL) using substances extracted from Bacillus sp. RH-5. The antioxidative substances produced extracellular in the culture broth by Bacillius sp. RH-S was obtained by elution of chloroform : methanol from silicagel column (80cm x100cm) chromatography. Band 4 eluted from fraction 3 by TLC was appeared at highest level of antioxidative activity using thiocyanate methed. Band 4 at a concentration of 100 or 200$\mu$g/$m\ell$ inhibited oxidation of LDL induced by the mouse transformed macrophage. According to IR. NMR or GC/MASS, the antioxidant substance was identified as 5-hydroxyindole.

• Journal of the Korea Institute of Military Science and Technology
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• v.3 no.1
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• pp.164-175
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• 2000

Three compounds of Cu(II)-loaded N,N,N'-trimethylethylenediaminated Merrifield-type polymers were synthesized with yields higher than 80%, and the hydrolysis reaction rates of O-isopropylmethyl-phosphonofluoridate(GB) and O-pinacolylmethylphosphonofluoridate (GD) catalyzed by them have been surveyed. GB and GD hydrolysis by Cu(II)-loaded polymers occurs via intermediate complex mechanism where rapid equilibrium to form intermediate complex between substrate and Cu(II)-loaded polymers($K_f$) is followed by rate determining hydrolysis step($k_1$). The measured activation parameters for $k_1$ are ${\Delta}H^{\ddag}$ : $17.75{\pm}0.98kJ/mol$ ${\Delta}S^{\ddag}$ / : $-218.42{\pm}3.35J/mol$ K, $E^{\circ}_a$ : $20.22{\pm}0.98kJ/mo1$ for GB and ${\Delta}H^{\ddag}$ / : $11.16{\pm}1.15kJ/mol,$${\Delta}S^{\ddag}$ /: $-258.57{\pm}3.93J/mol$ K, $E^{\circ}_a$ : $13.64{\pm}1.15 kJ/mol$ for GD. Standard enthalpy/entropy changes corresponding to the intermediate complex formation constant $K_f$ are ${\Delta}H^{\circ}$ : $37.05{\pm}2.19 kJ/mo1,$$ {\Delta}S^{\circ}$ : $163.12{\pm}7.49 J/mol$ K and ${\Delta}H^{\circ}$ : 418.59{\pm}2.04 kJ/mol,$ ${\Delta}S^{\circ}$ : 4111.92{\pm}6.98 J/mol$ K for GB and GD, respectively, The electron push-pull mechanism by Cu(II)-loaded polymers lowers the P-F bond breaking energy(~400 kJ/mol) to less than 1/20 compared to the case in which no Cu(II)-loaded resin presents. Analysis of $K_f$ and 4k_1$ over pH=6.5~8.0 range suggest that the GB and GD hydrolysis occurs intramolecularily with $pK_a$ =7.29 for ligated $H_2O$ and $t_{1/2}$=36.9 sec, $pK_a$ = 7.06 and $t_{1/2}$=177.7 sec for GB and GD, respectively.

• Journal of the Korean Applied Science and Technology
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• v.31 no.4
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• pp.541-548
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• 2014

This study was performed to obtain high conversion efficiency of $C_7H_8$ using non-thermal plasma and metal-supported catalyst. Adsorption-desorption characteristics of toluene was performed using 4A type (Zeolite) filled in a concentration reactor. Through this test, it was found that the concentration reactor has 0.020 g/g of adsorption capacity (at ambient temperature and pressure) and 3,600 ppm of desorption property at $150^{\circ}C$ (with in 20 min). In case of developed catalyst, toluene decomposition rate of Pd-AO (Pd coated catalyst) was better than Pd/Cu-AO and Pd/Ag-AO (Pd/Ag composite metal catalyst). Developed non-thermal plasma system was obtained flame amplification effect using injection process of desorbed tolune, and 98% of removal efficiency.

• Microbiology and Biotechnology Letters
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• v.20 no.2
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• pp.150-155
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• 1992

- Some properties of an extracellular cytosine deaminase excreted from an isolate from soil samples were examined after 20~80%' ammonium sulfate fractionation. The enzyme catalyzed the conversion of cytosine and 5-fluorocytosine into uracil and 5-fluorouracil by substrate specificity, respectively. The optimum temperature and storage time on the stability of the enzvme preparation were below $50^{\circ}C$ keeping above 90% of the residual activity and near 4 days keeping above 80% of the residual one in Tris-HCI buffer. The maximum activity was also obtained at 8.0 in pH and 37'C in temperature. The pHs and temperatures for enzyme activity ranged from 8.0~8.5 and from 37~$45^{\circ}C$. respectively. The presence of $Ag^-,Hg^{2-}, Zn^{2-}, Cu^{2-}, Sn^{2-}, \; or\; Pb^{2-}$ in the reaction mixture resulted in the marked inhibition in enzyme activity, but 1 mM of $K^+, Fe^[3+}, Mg^{2+}, \; or \; Na^+$. slightly increased the activity. The enzyme preparation was heavily affected by most of inhibitors tested such as 1 mM of EIITA, NaCN and pentachlorophenol, and completely inactivated by p-CMB and TCA of 1 mM, or 10 mM.

• Analytical Science and Technology
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• v.25 no.3
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• pp.171-177
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• 2012

A determination method of aromatic amino acids such as trytophan (Trp), tyrosine (Tyr), and phenylalanine (Phe) using luminol-$H_2O_2$-Cu(II) system has been presented. In the presence of an aromatic amino acid, the enhanced chemiluminescence (CL) intensity of luminol-$H_2O_2$-Cu(II) system was obtained by forming a complex between Cu(II) and the amino acid. Based on the above phenomenon, a sensitive and fast determination of three aromatic amino acids was performed using the CL method in batch-type detection system. To optimize determination conditions, the kinetic influence of an aromatic amino acid on the luminol-$H_2O_2$-Cu(II) system and the effects of $H_2O_2$ and Cu(II) concentration, pH, and buffers were investigated. Under the optimized conditions, the calibration curve was linear over the range from $1.0{\times}10^{-6}$ to $2.0{\times}10^{-5}\;M$ for Trp, $1.0{\times}10^{-6}$ to $2.0{\times}10^{-5}\;M$ for Try, and $2.0{\times}10^{-6}$ to $2.0{\times}10^{-5}\;M$ for Phe, respectively. In this range, reproducibility (RSD, n = 4) of Trp, Try, and Phe were 3.21%, 2.64%, and 2.48%, respectively. The limit of detection ($3{\sigma}/s$) was calculated to be $6.8{\times}10^{-7}\;M$ for Trp, $5.7{\times}10^{-7}\;M$ for Try, and $9.6{\times}10^{-7}\;M$ for Phe.

• Journal of Life Science
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• v.25 no.3
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• pp.345-348
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• 2015

An organic solvent stable lipase from solvent-tolerant Pseudomonas sp. BCNU 171 had an optimal pH of 8 and an optimal temperature of 37℃. This crude extracellular lipase from BCNU 171 exhibited increased stability in the presence of various types of solvents at high concentrations (25%, v/v). The lipase stability was found to be highest in the presence of xylene (137%), followed by toluene (131%), octane (130%), and butanol (104%). Overall, BCNU 171 lipase tended to be more stable than immobilized commercial lipase (Novozyme435) in the presence of organic solvents. Furthermore, BCNU 171 lipase maintained about 90% of its enzyme original activity in the presence of NH₄⁺, Na⁺, Ba²⁺, Hg²⁺, Ni²⁺, Cu²⁺, and Ca²⁺ion and significantly increased its enzyme activity in the presence of various emulsifying agents. Thus, the organic solvent stable lipase from Pseudomonas sp. BCNU 171 could be usable as a potential whole cell biocatalyst and for synthetic applications of enzymes for industrial chemical processes in organic solvents without using immobilization.