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1. Spectroscopic and Biological Studies of Phenanthroline Compounds: Selectively Recognize Gene Promoter G-quadruplex DNAs over Duplex DNA | |||
Wang Lihua,Wei Chunying | |||
Chemistry 14 December 2012 | |||
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Abstract:G-quadruplex DNA formed in the promoter regions of proto-oncogenes would block the transcription process and eventually suppress the development of tumors, so compounds that stabilize G-quadruplex DNA are potential antitumor drugs. This paper studied interactions of three phenanthroline compounds a-c with proto-oncogene c-kit2 and c-myc G-quadruplex DNAs by means of polymerase chain reaction (PCR) stop assay, fluorescence resonance energy transfer melting (FRET melting) assay, fluorescence indicator displacement (FID) assay, UV-vis absorption, fluorescence and circular dichroism (CD) spectroscopies. Results showed that all three compounds presented selectivity for the G-quadruplex over duplex, with binding constants (Ka) for the both quadruplexes varied from 0.49 x 106 to 3.32 x 106 M-1 (4.1- to 33.2-fold specificity). Compounds a, b and c were potential stabilizers for the c-kit2 G-quadruplex with the melting temperature increase (ΔTm) values of 12-15 oC. CD spectra indicated that the three compounds disrupted the structures of c-kit2 G-quadruplex, whereas no significant change was observed for c-myc G-quadruaplex. | |||
TO cite this article:Wang Lihua,Wei Chunying. Spectroscopic and Biological Studies of Phenanthroline Compounds: Selectively Recognize Gene Promoter G-quadruplex DNAs over Duplex DNA[OL].[14 December 2012] http://en.paper.edu.cn/en_releasepaper/content/4499807 |
2. Thermokinetic characterization of imipenem hydrolysis with metallo-β-lactamase CcrA from Bacteroides fragilis | |||
Zhai Le ,Yang Kewu ,Liu Chengcheng ,Gao Huizhou,Yang Xia,Shi Ying,Wen Jing | |||
Chemistry 26 December 2011 | |||
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Abstract:Imipenem is a widely used carbapenem antibiotic clinically. In an effort to probe the antibiotic resistance in bacteria, we first report in this paper the thermokinetic parameters of the imipenem hydrolysis with B1 subclass metallo-β-lactamase CcrA from Bacteroides fragilis. The values of activation free energy are 87.540 ± 0.027, 88.781 ± 0.031, 89.901 ± 0.036, and 91.057 ± 0.021 kJomol-1 at 293.15, 298.15, 303.15, and 308.15 K, respectively, the activation enthalpy is 19.099 ± 0.005 kJomol-1, the activation entropy is -233.57 ± 0.09 Jomol-1oK-1 and the apparent activation energy E is 21.598 kJomol-1. The results indicated that the imipenem hydrolysis by CcrA was an exothermic and spontaneous reaction with order of 1.4 and had higher activation enthalpy and lower activation entropy than the cefazolin hydrolysis. | |||
TO cite this article:Zhai Le ,Yang Kewu ,Liu Chengcheng , et al. Thermokinetic characterization of imipenem hydrolysis with metallo-β-lactamase CcrA from Bacteroides fragilis[OL].[26 December 2011] http://en.paper.edu.cn/en_releasepaper/content/4457650 |
3. Structural and functional insights into polymorphic enzymes of cytochrome P450 2C8 | |||
Jiang Hualin,Tan Xiangshi | |||
Chemistry 28 September 2011 | |||
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Abstract:The cytochrome P450 (CYP) superfamily plays a key role in the oxidative metabolism of a wide range of drugs and exogenous chemicals. CYP2C8 is the principal enzyme responsible for the metabolism of the anti-cancer drug paclitaxel in the human liver. Nearly all previous works about polymorphic variants of CYP2C8 were focused on unpurified proteins, either cells or human liver microsomes; therefore their structure-function relationships were unclear. In this study, two polymorphic enzymes of CYP2C8 (CYP2C8.4 (I264M) and CYP2C8 P404A) were expressed in E. coli and purified. Metabolic activities of paclitaxel by the two purified polymorphic enzymes were observed. The activity of CYP2C8.4 was 25% and CYP2C8 P404A was 30% of that of WT CYP2C8, respectively. Their structure-function relationships were systematically investigated for the first time. Paclitaxel binding ability of CYP2C8.4 increased about two times while CYP2C8 P404A decreased about two times than that of WT CYP2C8. The two polymorphic mutant sites of I264 and P404, located far from active site and substrate binding sites, significantly affect heme and/or substrate binding. This study indicated that two important nonsubstrate recognition site (SRS) residues of CYP2C8 are closely related to heme binding and/or substrate binding. This discovery could be valuable for explaining clinically individual differences in the metabolism of drugs and provides instructed information for individualized medication. | |||
TO cite this article:Jiang Hualin,Tan Xiangshi. Structural and functional insights into polymorphic enzymes of cytochrome P450 2C8[OL].[28 September 2011] http://en.paper.edu.cn/en_releasepaper/content/4444533 |
4. The progress of acylase-catalyzed addition and its tandem reaction in organic media | |||
Bokai Liu,Xianfu Lin | |||
Chemistry 12 January 2010 | |||
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Abstract:Enzymatic promiscuity, namely the possibility that one active site of an enzyme can catalyze several different chemical transformations, has been paid more attention and valuable synthesis tool for synthetic chemistry. This mini-review will focus on promiscuous acylase-mediated reactions that are useful in organic synthesis. The examples of catalytic promiscuity in Michael addition, Markovnikov addition by acylase and cascade reaction for the synthesis of pyrimidine derivatives with sugar branch are reviewed. | |||
TO cite this article:Bokai Liu,Xianfu Lin. The progress of acylase-catalyzed addition and its tandem reaction in organic media[OL].[12 January 2010] http://en.paper.edu.cn/en_releasepaper/content/38827 |
5. Controllable Enzymatic anti-Markovnikov, Markovnikov Addition and Acylation of Thiols to Vinyl Esters in Organic Media | |||
Wu Qi ,Lin Xianfu | |||
Chemistry 11 January 2010 | |||
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Abstract:A novel enzymatic promiscuous protocol for the reaction of thiols to vinyl esters has been described. The acylation is efficiently catalyzed by commercially available D-amino acylase from Escherichia coli (DA) in DMF, affording the thiolesters in good yields. Moreover, the regioselectivity of the Markovnikov and anti-Markovnikov reaction can be controlled by the choice of organic media under the catalysis of Candida antarctica lipase B (CAL-B) so that both the anti-Markovnikov (DMF) and the Markovnikov products (Isopropylether) are now easily accessible in excellent selectivities. | |||
TO cite this article:Wu Qi ,Lin Xianfu . Controllable Enzymatic anti-Markovnikov, Markovnikov Addition and Acylation of Thiols to Vinyl Esters in Organic Media[OL].[11 January 2010] http://en.paper.edu.cn/en_releasepaper/content/38725 |
6. Enantioselective Synthesis of Silicon Containing Cyanohydrin: (R)-2-trimethylsilyl-2-hydroxyl-ethycyanide by Oxynitrilase from Plum | |||
Liu Senlin,Zong Minhua,Huang Shunrong | |||
Chemistry 18 May 2006 | |||
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Abstract:The enantioselective transcyanation of acetyltrimethylsilane with acetone cyanohydrin catalyzed by (R)-oxynitrilases from plum seed meal in an aqueous/organic biphasic system for the preparation of (R)-2-trimethylsilyl-2-hydroxyl-ethylcyanide was successfully carried out. For optimization of the reaction, the influences of some important factors on the plum oxynitrilase-catalyzed reaction were investigated. Diisopropyl ether was found to be the best organic phase for the reaction among all the organic solvents explored. The optimal buffer pH and aqueous phase content were 5.0 and 13% (V/V), respectively, under which substrate conversion and product enantiomeric excess were 99% and 99%, respectively. | |||
TO cite this article:Liu Senlin,Zong Minhua,Huang Shunrong. Enantioselective Synthesis of Silicon Containing Cyanohydrin: (R)-2-trimethylsilyl-2-hydroxyl-ethycyanide by Oxynitrilase from Plum[OL].[18 May 2006] http://en.paper.edu.cn/en_releasepaper/content/6678 |
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