Adsorción de Cd(II) y Pb(II) presentes en solución acuosa con hueso de nanche (Byrsonima crassifolia) / Adsorption of Cd(ll) and Pb(ll) present in aqueous solution with nanche stone (Byrsonima crassifolia) / Adsorção de Cd(ll) e Pb(ll) presente em solução aquosa com osso nanche (Byrsonima crassifolia)

Resumen El hueso de nanche es un residuo agrícola con gran potencial de uso como adsorbente. Al respecto, se evaluó la capacidad de adsorción de iones Cd(II) y Pb(II), presentes en solución acuosa, utilizando este residuo. Las pruebas realizadas en este estudio fueron: la determinación del punto de carga cero (pHPZC), determinación de sitios activos (método de Boehm y espectroscopía FTIR) y el desarrollo de los modelos matemáticos de Langmuir, Freundlich y Prausnitz-Radke, a través de isotermas de adsorción. Los resultados obtenidos del pHPZC del hueso de nanche estuvieron en un rango ácido (6,0), mientras que la concentración de sitios ácidos y básicos fue de 0,1037 y 0,046 mol/g, respectivamente. Los espectros infrarrojos (FTIR) detectaron sitios funcionales ácidos asociados al grupo fenol, ácidos carboxílicos y lactonas. Finalmente, la capacidad de adsorción del hueso de nanche para Cd(II) y Pb(II) se incrementó con el pH y alcanzó porcentajes de remoción hasta de 84 % para Cd(II) a pH 8, y de 82% para Pb(II) a pH 5. En conclusión, el pH y la presencia de sitios funcionales ácidos fueron determinantes en la eliminación de los iones Pb(II) y Cd(II).

Abstract The nanche stone is an agricultural residue that has great potential as adsorbent. Then, the adsorption capacity of Cd(II) and Pb(II) ions present in aqueous solution was evaluated, using the stone as adsorbent. The tests performed for this purpose were the determination of point of zero charge (pHPZC), determination of active sites (Boehm method and FTIR spectroscopy), and the development of the mathematical models of Langmuir, Freundlich, and Prausnitz-Radke through adsorption isotherms. The results obtained from the pHPZC of the nanche stone were in an acidic range (6,0), while the concentration of acid and basic sites were 0.1037 and 0.046 mol/g respectively. The infrared spectra (FTIR) detected acid functional sites associated with the phenol group, carboxylic acids, and lactones. Finally, the adsorption capacity of nanche stone to Cd(II) and Pb(II), increased with the pH, achieving percentages of removal up to 84% for Cd (II) to pH 8, and of 82% for Pb(II) to pH 5. In conclusion, the pH and the presence of acidic functional sites were decisive in the elimination of the Pb(II) and Cd(II) ions.

Resumo O osso Nanche é um resíduo agrícola que possui grande potencial como adsorvente, neste respeito, a capacidade de adsorção de íons Cd(II) e Pb(II) presentes em solução aquosa foi avaliada, utilizando osso como adsorvente. Os testes realizados para este fim foram a determinação do ponto zero de carga (pHPZC), a determinação de sites ativos (método Boehm e espectroscopia FTIR) e o desenvolvimento dos modelos matemáticos de Langmuir, Freundlich e Prausnitz-Radke através de isotermas de adsorção. Os resultados obtidos do pHPZC do osso nanche foram em uma faixa ácida (6,0), enquanto a concentração de ácidos e sites básicos foram 0,1037 e 0,046 mol / g, respectivamente. Os espectros de infravermelho (FTIR) detectaram sites funcionais ácidos associados ao grupo fenol, ácidos carboxílicos e lactonas. Finalmente, a capacidade de adsorção do osso nanche para Cd(II) e Pb(II), aumentou com o pH, atingindo porcentagens de remoção de até 84% para o Cd(II) em pH 8, e 82% para Pb(II) a pH 5. Em conclusão, o pH e a presença de sites funcionais ácidos foram decisivos na eliminação dos íons Pb (II) e Cd (II).

A preliminary study of binding site on β-tubulin interacting with the new anti-cancer drug docetaxel / 国际生物医学工程杂志

Objective To study the interaction mechanism of anti-cancer drug docetaxel (DTX) andβ-tubulin, to determine the binding sites and the involved amino acids between the β-tubulin and docetaxel, and to analyze the dynamic combination process. Methods The docking binding energy and interaction sites of DTX molecules withβ-tubulin on the potential energy surface were calculated by molecular docking method. The dynamic interaction process of the low binding energy DTX with β-tubulin was simulated by molecular dynamics method. Results The results of molecular docking showed that there are three interaction sites, including N1, N2 and N3, between DTX and β-tubulin. The DTX molecules with structure of No.1, 2 and 4, which have excellent docking energy, were chose for molecular dynamics simulation. As a result, the dynamic change processes of the system complexes from non-equilibrium to equilibrium were obtained. The simulation results showed that the hydrogen bonds formed by the DTX with structure No.1 were significantly higher than those with structures No. 2 and 4. The solvent accessibility surface area of the DTX with structures No.1, 2 and 4 was higher than that of paclitaxel. Conclusion The model of DTX binding toβ-tubulin was established, which could provide theoretical guidance for the design and development of novel paclitaxel anticancer drugs.

Screening on Active Sites and the Best Compatibility of NewYouguiyin Prescription / 世界科学技术-中医药现代化

This study was aimed to clarify the main active site and the best compatibility of the newYouguiyin prescription. The rat osteoblast-like cells was used as model cells. The investigation was made on the impact of different extraction parts of each herb and their compatibility on osteoblast proliferation. The results showed that the compatibility of butyl alcohol part fromDipsacus,Epimedium andCnidium had the most significant proliferation of osteoblast activity. It was concluded that the screening of active sites and the best compatibility of newYouguiyin prescription had laid the foundation for the development of subsequent innovation for traditional Chinese medicine (TCM).

DNA Polymerases: An Insight into Their Active Sites and Catalytic Mechanism.

To analyze the active sites of various prokaryotic and eukaryotic DNA polymerases and propose a plausible mechanism of action for the polymerases with the Escherichia coli DNA polymerase I as a model system. Study Design: Bioinformatics, Biochemical and X-ray crystallographic data were analyzed. Place and Duration of Study: Department of Molecular Microbiology, School of Biotechnology, Madurai Kamaraj University, Madurai – 625 021, India. From 2007 to 2012. Methodology: The advanced version of T-COFFEE was used to analyze both prokaryotic and eukaryotic DNA polymerase sequences. Along with this bioinformatics data, X-ray crystallographic and biochemical data were used to confirm the possible amino acids in the active sites of different types of polymerases from various sources. Results: Multiple sequence analyses of various polymerases from different sources show only a few highly conserved motifs among these enzymes except eukaryotic epsilon polymerases where a large number of highly conserved sequences are found. Possible catalytic/active site regions in all these polymerases show a highly conserved catalytic amino acid K/R and the YG/A pair. A distance conservation is also observed between the active sites. Furthermore, two highly conserved Ds and DXD motifs are also observed. Conclusion: The highly conserved amino acid K/R acts as the proton abstractor in catalysis and the YG/A pair acts as a “steric gate” in selection of only dNTPS for polymerization reactions. The two highly conserved Ds act as the “charge shielder” of dNTPs and orient the alpha phosphate of incoming dNTPs to the 3’-OH end of the growing primer.

Bacterial citrate lyase.

Bacterial citrate lyase, the key enzyme in fermentation of citrate, has interesting structural features. The enzyme is a complex assembled from three non-identical subunits, two having distinct enzymatic activities and one functioning as an acyl-carrier protein. Bacterial citrate lyase, si-citrate synthase and ATP-citrate lyase have similar stereospecificities and show cofactor cross-reactions. On account of these common features, the citrate enzymes are promising markers in the study of evolutionary biology. The occurrence, function, regulation and structure of bacterial citrate lyase are reviewed in this article.