• Journal of Industrial and Engineering Chemistry
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• 제67권
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• pp.461-468
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• 2018

A highly sensitive, selective and rapid method for the determination of lead based on the reaction of lead (II) with 5-(4'-chlorophenylazo)-6-hydroxypyrimidine-2,4-dione (CPAHPD) and the solid phase extraction of the Pb(II)-CPAHPD complex with Amberlite XAD-2000 was developed, in the presence of pH 5.6 buffer solution and Triton X-114 medium. CPAHPD reacts with lead to form a violet complex with a molar ratio of 2:1 (CPAHPD to lead). This complex was enriched by the solid phase extraction with Amberlite XAD-2000. An enrichment factor of 500 was obtained by elution of the complex from the resin with a minimal amount of isopentyl alcohol(0.2 mL). In isopentyl alcohol medium,the molar absorptivity of the complex is $1.13{\times}10^6L\;mol^{-1}cm^{-1}$ at 647 nm. Beer's law is obeyed in the range of $5.0-160ng\;mL^{-1}$ in the measured solution. The relative standard deviation for 10 replicate samples of $50ng\;mL^{-1}$ level is 1.26%. The detection and quantification limits reaches 1.5 and $4.7ng\;mL^{-1}$ in the original samples. The presented procedure was successfully applied for determination of lead content in real samples such as vegetables, waters, biological and soil samples with satisfactory results.

• Journal of Microbiology and Biotechnology
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• 제19권7호
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• pp.727-733
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• 2009

Heat shock protein 70 kDa (hsp70), a molecular chaperone involved in folding of nascent proteins, has been studied for its ability to activate innate and specific immunity. High purity hsp70 preparation is generally required for immunization experiments, because endotoxins and other immunologically active contaminants may affect immune responses independently of hsp70. We have developed a novel modification of E. coli-expression medium that enabled a simple two-step production and purification method for endotoxin-free recombinant hsp70. During Ni-NTA-based affinity purification of hsp70, a contaminating protein from host E. coli cells, L-glutamine-n-fructose-6-phosphate aminotransferase (GFAT), was identified. By testing various compounds, supplementation of growth medium with a GFAT metabolite,N-acetylglucosamine, was found to reduce GFAT expression and increase the total hsp70 yield five times. The new protocol is based on column purification of His-tagged hsp70 protein produced by E. coli with the modified medium, followed by endotoxin removal by Triton X-114 extraction. This approach yielded hsp70 with high purity and minimal endotoxin contamination, making the final product acceptable for immunization experiments. In summary, a simple modification of growth medium allowed production of recombinant mouse hsp70 in high yield and purity, thus compatible with immunological studies. This protocol may be useful for production of other Histagged proteins expressed in E. coli.

• 약학회지
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• 제48권6호
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• pp.384-390
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• 2004

Polyphenol oxidase-catalyzed oxidation of substrates (t-butylcatechol, 4-methylcatechol, chlorogenic acid, caffeic acid and pyrocatechol) were performed in the Ph range 4~8. Co ncentrations of substrate's major oxidation products were monitored by high performance liquid chromatograph. The nature and amounts of products formed were highly pH dependent. They also were ifluenced by kinds of substrates. Major oxidation product of 4-methylcatechol appeared the maxium value at pH 5, them of chlorogenic acid, caffeic acid and pyrocatechol at pH 6.0 and that of t-butylcatechol at pH 5~7. Time-dependent PPO activity was determined at $4^{\circ}C\;and\;30^{\circ}C$. PPO extracted by phosphate buffer containing triton X-114 (t-PPO) was more stable than PPO by phosphate buffer (b-PPO). The result of electrophoresis, at first PPO was showed only a band at 48 kd. After 1~3 days a partial degrade band was appeared in b-PPO and three partial degrade bands in t-PPO. No activity band was appeared in PPOs at $30^{\circ}C$ and b-PPO at $4^{\circ}C$ after 4 days. And a band (37 kDa) in t-PPO was remained finally and disappered. PPO from Perillae leaves has two activity bands at 48 and 37 kDa in previous paper. It was supposed that PPO in the leaves of Perilla frutescens was a protein having one molecular weight as 48 kDa. And 37 kDa protein, relatively proteolysis-resistant, was a proteolyzed form of a major form.

• 폴리머
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• 제39권2호
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• pp.329-337
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• 2015

본 연구에서는 다중벽 탄소나노튜브(MWCNTs)를 질산과 황산의 혼산으로 산화시켜 표면에 카르복시기를 도입 후, $SOCl_2$와 1,4-butanediol을 사용하여 MWCNT-OH를 제조하였다. 제조된 MWCNT-OH는 3-methacryloxypropyltrimethoxylsilane(MPTMS)와 실란화 반응으로 methacrylate기가 도입된 MWCNT-MPTMS를 제조하였다. MWCNT-MPTMS와 methyl methacrylate(MMA)를 사용하여 유화중합법으로 MWCNT-MPTMS/PMMA 복합 입자를 제조하였다. 음이온 계면 활성제인 sodium dodecylbenzene sulfonate(SDBS)를 사용하여 유화중합한 MWCNT-MPTMS/PMMA는 균일한 입도, 좁은 입도분포 및 계면에서의 화학결합으로 인하여 $T_g$가 순수 MWCNT를 사용하여 중합한 시료보다 $3.4^{\circ}C$ 높아짐을 확인하였다.