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Purification and Characterization of an Extracellular Protease from Bacillus pumilus CN8
Jin, Yong-Guo,Li, Hao-Li,Mal, Mei-Hu,Wang, Jun,Kim, Ha-Na,Oh, Deog-Hwan The Korean Society of Food Hygiene and Safety 2011 한국식품위생안전성학회지 Vol.26 No.1
The protease produced by a Bacillus pumilus CN8 strain was purified by DEAE-Cellulose-52 ion exchange. It has a molecular weight of approximately 96,920 Dalton. In the present study, this protease showed strong activity over a broad range of pH (6.5-9.5) and temperature from $40^{\circ}C$ to $60^{\circ}C$, and the protease performed the maximal activity at pH 7.3 at $42^{\circ}C$. The effect of metal ions on protease activity showed that $K^+$ could slightly increase the protease activity, and other ions such as $Zn^{2+}$, $Fe^{2+}$, $Na^+$, $Ca^{2+}$, $Mg^{2+}$ had no significant activation or inhibition to the protease (P> 0.05), and the more important is that $Cu^{2+}$, $Mn^{2+}$, $Sn^{2+}$, $Cd^{2+}$ had a strong inhibitory effect on the protease activity.
Wu, Yong,Jin, Lu,Xue, Ying,Xie, Dai Qian,Kim, Chan Kyung,Guo, Yong,Yan, Guo Sen Wiley Subscription Services, Inc., A Wiley Company 2008 Journal of computational chemistry Vol.29 No.8
<P>The hydrolysis reaction of N,N-dimethyl-N′-(2-oxo-1, 2-dihydro-pyrimidinyl)formamidine (DMPFA), a model compound of the antivirus drug amidine-3TC (3TC = 2′, 3′-dideoxy-3′-thiacytidine), is investigated by the hybrid density functional theory B3LYP/6-31+G (d,p) method. The hydrolysis reaction of the title compound is predicted to undergo via two pathways, each of which is a stepwise process. Path A is the addition of H<SUB>2</SUB>O to the C&n.dbond;N double bond in the amidine group to form a tetrahedral structure in its first step, and then the transfer of the H atom of hydroxyl leads to the corresponding products via four possible channels. Path B simultaneously involves the nucleophilic attack of H<SUB>2</SUB>O to the C atom of the C&n.dbond;N bond and the proton transfer to the N atom of amino group leading to the cleavage of the C&n.bond;N single bond in the amidine group. The results indicate that path A is more favorable than path B in the gas phase. Moreover, to simulate the title reaction in aqueous solution, water-assisted mechanism and the cluster-continuum model, based on the SCRF/CPCM model, are taken into account in our work. The results indicate that it is rational for two water molecules served as a bridge to assist in the first step of path A and that cytosine rather than the cytosine-substituted formamide should be released from the tetrahedral intermediate via s six-membered cycle transition state (channel 2). Our calculations exhibit that the process toward the tetrahedral intermediate is the rate-determining step both in the gas phase and in aqueous solution. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008</P> <B>Graphic Abstract</B> <P> <img src='wiley_img/01928651-2008-29-8-JCC20883-gra001.gif' alt='wiley_img/01928651-2008-29-8-JCC20883-gra001'> </P>
Guo-jin Tan,Yong-chun Cheng,Han-bing Liu,Long-lin Wang 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.38 No.3
Input excitation and output response of structure are needed in conventional modal analysis methods. However, input excitation is often difficult to be obtained in the dynamic load test of bridge structures. Therefore, what attracts engineers’ attention is how to get dynamic parameters from the output response. In this paper, a structural experimental modal analysis method is introduced, which can be used to conveniently obtain dynamic parameters of the structure from the free decay response. With known damping coefficients, this analysis method can be used to identify the natural frequencies and the mode shapes of MDOF structures. Based on the modal analysis theory, the mathematical relationship of damping ratio and frequency is obtained. By using this mathematical relationship to improve the previous method, an improved experimental modal analysis method is proposed in this paper. This improved method can overcome the deficiencies of the previous method, which can not identify damping ratios and requires damping coefficients in advance. Additionally, this improved method can also identify the natural frequencies, mode shapes and damping ratios of the bridge only from the free decay response, and ensure the stability of identification process by using modern mathematical means. Finally, the feasibility and effectiveness of this method are demonstrated by a numerical example of a simply supported reinforced concrete beam.
IN SITU UNZIPPING OF CARBON NANOTUBES TO FORM GRAPHENE NANORIBBONS
YONG-SHENG ZHOU,PAN JIN,TENG GUO,YING-CHUN ZHU,GAO-HUI DU,BING-SHE XU 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2014 NANO Vol.9 No.1
We report the one step facile synthesis of graphene nanoribbons (GNRs) by unzipping carbonnanotubes (CNTs) from glucose (C 6 H 12 O 6 ) precursor, using a simple chemical vapor depositionmethod. Some nanotubes are partially cut resulting in a GNR – CNT hybrid whereas others arefully cut to form GNRs. The average length of GNRs achieved by this method is typically in therange of 1 – 10 ? m. The formation of GNRs is ascribed to the in situ oxygen-driven unzipping ofCNTs. The process is free from aggressive oxidants and utilizes the in situ unzipping. Thismethod o®ers an alternative approach for making GNRs, compared to previously used techniquesto synthesize GNRs.
Synthesis and Evaluation of Antitumor Activity
Jin, Guang-Zhu,Song, Gyu-Yong,Zheng, Xiang-Guo,Kim, Yong,Sok, Dai-Eun,Ahn, Byung-Zun The Pharmaceutical Society of Korea 1998 Archives of Pharmacal Research Vol.21 No.2
Fourty eight derivatives of 2-(1-oxyalkyl)-1,4-dioxy-9,10-anthraquinone were synthesized, and their antitumor activity was evaluated. On the whole, 2-(1-hydroxyalkyl)-1,4-dihydroxy-9,10-anthraquinones (DHAQ=1,4-dihydroxy-9,10-anthraquinone) showed stronger cytotoxic activity against L1210 cells than 2-(l-hydroxyalkyl)-1,4-dimethoxy-9,10-anthraquinones(DMAQ =1,4-dimethoxy-9,10-anthraquinone), implying that free hydroxy groups at C-1 and C-4 of the anthraquinone structure are necessary for the cytotoxic activity. The bioactivity of 2-(lhydroxyalkyl)-DHAQ derivatives differed according to the size of alkyl group at C-1;while the elongation of alkyl group over 7 carbon atoms failed to enhance the bioactivity, the derivatives possessing alkyl moiety of 1-6 carbon atoms showed an increase in the cytotoxicity and the antitumor activity in Sarcoma-180; 2-hydroxymethyl-DHAQ ($ED_{50}$, $15\mu\textrm{g}$/ml; T/C, 125%), 2-(1 -hydroxyethyl)-DHAQ($1.9{\mu}g/ml;139.2%)$;, 2-(1-hydroxypropyl)-DHAQ ($7.2{\mu}g$/ml; 135.1%), 2-(1-hydroxybutyl)-DHAQ ($10.2{\mu}g/ml; 125.3%)$, 2-(1-hydroxypentyl)-DHAQ ($23.7{\mu}g/ml; 110.1%$). and 2-(1-hydroxyhexyl)-DHAQ ($58{\mu}g/ml;108%$). Next, 2-(1-Hydroxyalkyl)-DHAQ derivatives were acetylated to produce 2-(1-acetoxyalkyl)-DHAQ analogues. Although the acetylation somewhat enhanced the cytotoxicity, but not the antitumor action. In addition, the presence of phenyl group at $C-1^{l}$ enhanced the cytotoxicity and the T/C value, compared to alkyl groups of same size; 2-(1-hydroxy-1-phenyl)-DHAQ ($ED_{50}$, $5.6{\mu}g$, T/C, 137%).
A Benzobisimidazolium-Based Fluorescent and Colorimetric Chemosensor for CO<sub>2</sub>
Guo, Zhiqian,Song, Na Ri,Moon, Jong Hun,Kim, Myounwoo,Jun, Eun Jin,Choi, Jiyoung,Lee, Jin Yong,Bielawski, Christopher W.,Sessler, Jonathan L.,Yoon, Juyoung American Chemical Society 2012 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.134 No.43
<P>A new sensor for the fluorescent and colorimetric detection of CO<SUB>2</SUB> is described. The system utilizes fluoride to activate a tetrapropyl benzobisimidazolium salt and operates in the absence of an exogenous base. On the basis of spectroscopic and theoretical analyses, the mode of action of the present system is ascribed to the fluoride-induced formation of an N-heterocyclic carbene intermediate that reacts with CO<SUB>2</SUB> to form an imidazolium carboxylate.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2012/jacsat.2012.134.issue-43/ja306891c/production/images/medium/ja-2012-06891c_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja306891c'>ACS Electronic Supporting Info</A></P>