• Bulletin of the Korean Chemical Society
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• 제34권9호
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• pp.2741-2746
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• 2013

The immobilization of enzyme is one of the key issues both in the field of enzymatic research and industrialization. In this work, we reported a facile method to immobilize Candida Antarctica lipase B (CALB) in alginate carrier. In the presence of calcium cation, the enzyme-alginate suspension could be cross-linked to form beads with porous structure at room temperature, and the enzyme CALB was dispersed in the beads. Activity of the enzyme-alginate composite was verified by enzymatic hydrolysis reaction of p-nitrophenol butyrate in aqueous phase. The effects of reaction parameters such as temperature, pH, embedding and lyophilized time on the reactive behavior were discussed. Reuse cycle experiments for the hydrolysis of p-nitrophenol butyrate demonstrated that activity of the enzyme-alginate composite was maintained without marked deactivation up to 6 repeated cycles.

• 공업화학
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• 제19권3호
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• pp.351-356
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• 2008

비이온성의 N P-10 (Polyoxyethylene Nonylphenol Ether: $C_9H_{19}C_6H_4(OCH_2CH_2)_{10}OH$) 계면활성제를 사용하여 나노크기의 $TiO_2$를 제조하였으며, TGA-DTA TEM, XRD, FT-IR 등을 사용하여 마이크로에멀젼을 이용한 나노입자 제조시 $W_o$ ($H_2O/AOT$)비에 따른 입자의 크기 및 결정성 등 물리적 성질을 조사하였다. 또한 제조된 $TiO_2$ 나노입자의 광촉매적 특성을 알아보기 위해 회분식 반응장치를 이용하여 p-nitrophenol의 광분해반응의 활성을 조사하였다. 제조된 $TiO_2$ 나노입자는 $300{\sim}600^{\circ}C$의 소성온도 범위에서 anatase 구조가 형성되었으며, 소성온도 $700^{\circ}C$에서 anatase 구조에서 rutile 구조로 전이되기 시작하였다. 입자크기는 $W_o$ 비가 증가함에 따라 증가하였고, 반면에 p-nitrophenol의 광분해반응에서 반응성은 감소하였다. 또한 $400{\sim}500^{\circ}C$에서 소성된 $TiO_2$ 촉매가 순수한 anatase 구조를 가지며 가장 높은 p-nitrophenol 분해활성을 보여주었다.

• Bulletin of the Korean Chemical Society
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• 제15권11호
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• pp.1001-1003
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• 1994

A series of phosphodiesters of p-nitrophenyl phosphoryl derivatives were synthesized and used as a model substrate for phospholipase D (PLD). The phosphodiester substrates were synthesized from p-nitrophenyl phosphorodichloridate and corresponding alcohols with different chain lengths and polar groups. To measure the activity of PLD, either spectroscopic method for p-nitrophenol or pH-stat titration method was employed. For each substrate, effects of substrate concentration, pH, and $Ca^{2+}$ ion were examined. The kinetic parameters $V_{max}$ for the different substrates were varied depending on the chain lengths or charge of the alcohols. No calcium effect was observed in the hydrolysis of neutral and negatively charged alcohol derivatives, while positively charged choline derivative showed a strong $Ca^{2+}$ ion dependence.

• Toxicological Research
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• 제22권1호
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• pp.1-8
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• 2006

The primary metabolism of pyribenzoxim was studied in rat liver microsomes in order to identify the cytochrome P450 (CYP) isoform(s) and esterases involved in the metabolism of pyribenzoxim. Chemical inhibition using CYP isoform-selective inhibitors such as ${\alpha}$-naphthoflavone, tolbutamide, quinine, chlorzoxazone, troleandomycin, and undecynoic acid indicated that CYP1A and CYP2D are responsible for the oxidative metabolism of pyribenzoxim. And inhibitory studies using eserine, bis-nitrophenol phosphate, dibucaine, and mercuric chloride indicated pyribenzoxim hydrolysis involved in microsomal carboxylesterases containing an SH group (cysteine) at the active center.

• 미생물학회지
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• 제29권2호
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• pp.85-91
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• 1991

.betha.-1,4-D-Glucan glucanohydrolase(EC 3.2.1.4;F-II-IV) purified from Trichoderma koningii was identified as a glycoprotein containing 9% carbohydrate. Isoelectric point of the enzyme was estimated to be 4.9 and molecular weight was determined to be approximately 58,000. The porducts of p-nitrophenyl-cellobioside ($PNPG_{2}$) catalyzed by the enzyme were p-nitrophenol(PNP) and p-nitrophenyl-glucoside($PNPG_{1}$). The Km value for $PNPG_{2}$ was estimated to be 0.97 mM in case of the holoside lindage and 10.4 mM in case of the aglycon linkage and their kcat values were $1.8*10^{5}$$ min^{-1}$ and $7.5*10^{5}$ $min^{-1}$ respectively. The product of p-nitrophenyl cellotriose($PNPG_{3}$) was only $PNPG_{1}$. The Km value for $PNPG_{3}$ was 69.5 .$\mu$M and kcat was $1*10^{8}$ $min^{-1}$ which implicates that the enzyme have higher affinity and higher hydrolysis rate toward $PNPG_{3}$ than toward $PNPG_{2}$. The enzyme showed its optimal activity at pH 4.0-4.5 and at 60.deg.C. The effect of gluconolactone on the activity toward $PNPG_{2}$ showed competitive inhibition pattern but glucose and cellobiose did not. The enzyme contained a high content of acidic and hydroxylated amino acids in contrast to basic amino acids.

• Korean Journal of Chemical Engineering
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• 제35권11호
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• pp.2220-2231
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• 2018

Lipase from Candida rugosa was immobilized on $MgO{\cdot}SiO_2$ hybrid grafted with amine, thiol, cyano, phenyl, epoxy and carbonyl groups. The products were analyzed using Fourier transform infrared spectroscopy, nuclear magnetic resonance, low-temperature $N_2$ sorption and elemental analysis. Additionally, the degree of coverage of the oxide material surface with different functional groups and the number of surface functional groups were estimated. The Bradford method was used to determine the quantity of immobilized enzyme. The largest quantity of enzyme (25-28 mg/g) was immobilized on the hybrid functionalized with amine and carbonyl groups. On the basis of hydrolysis reaction of p-nitrophenyl palmitate to p-nitrophenol, it was determined how the catalytic activity of the obtained biocatalysts is affected by pH, temperature, storage time, and repeated reaction cycles. The best results for catalytic activity were obtained for the lipase immobilized on $MgO{\cdot}SiO_2$ hybrids with amine and carbonyl groups. The biocatalytic system demonstrated activity above 40% in the pH range 4-10 and in the temperature range $30-70^{\circ}C$. Lipase immobilized on the $MgO{\cdot}SiO_2$ systems with amine and epoxy groups retains, respectively, around 80% and 60% of its initial activity after 30 days of storage, and approximately 60-70% after 10 reaction cycles.