Nanosized GdVO4 powders were synthesized via a sol-gel method using different carboxylic acids as chelating agent, followed by calcination at 600 ℃for 3 h. The effect of different carboxylic acids such as citric acid...Nanosized GdVO4 powders were synthesized via a sol-gel method using different carboxylic acids as chelating agent, followed by calcination at 600 ℃for 3 h. The effect of different carboxylic acids such as citric acid, malic acid, and tartaric acid on the characteristics of the nanosized GdVO4 powders was investigated. The GdVO4 powder was also synthesized without carboxylic acid for comparison. The thermal decomposition process of the car- boxylate precursors was investigated by thermogravimetric differential thermal analysis （TG-DTA）. X-ray diffraction （XRD）, Fourier transform infrared spectroscopy （FTIR）, field emission scanning electron microscope （FESEM）, transmission electron microscope （TEM）, and surface area measurement data were used to confirm the formation of nanocrystalline GdVO4 powders. It is found that the synthesis using the carboxylic acid with higher heat of combustion results in the powder with larger crystallite size. The difference in the steric effect of the acids used, which was evaluated by a computational method, also affects the degree of agglomeration of the synthesized powders.展开更多
BACKGROUND： P-glycoprotein （P-gp） is a 170-kDa membrane protein. It provides a barrier function and help to excrete toxins from the body as a transporter. Some bioflavonoids have been shown to block P-gp activity. ...BACKGROUND： P-glycoprotein （P-gp） is a 170-kDa membrane protein. It provides a barrier function and help to excrete toxins from the body as a transporter. Some bioflavonoids have been shown to block P-gp activity. OBJECTIVE： To evaluate the important amino acid residues within nucleotide binding domain 1 （NBD l） of P-gp that play a key role in molecular interactions with flavonoids using structure-based pharmacophore model. METHODS： In the molecular docking with NBD 1 models, a putative binding site of flavonoids was proposed and compared with the site for ATP. The binding modes for ligands were achieved using LigandScout to generate the P-gp-flavonoid pharmacophore models. RESULTS： The binding pocket for flavonoids was investigated and found these inhibitors compete with the ATP for binding site in NBD1 including the NBD1 amino acid residues identified by the in silico techniques to be involved in the hydrogen bonding and van der Waals （hydrophobic） interactions with flavonoids. CONCLUSION： These flavonoids occupy with the same binding site of ATP in NBD1 proffering that they may act as an ATP competitive inhibitor.展开更多
基金financially supported by the Chiang Mai University (CMU) Junior Research Fellowship Programthe National Research University (NRU) Project from Thailand's Office of the Higher Education Commission
文摘Nanosized GdVO4 powders were synthesized via a sol-gel method using different carboxylic acids as chelating agent, followed by calcination at 600 ℃for 3 h. The effect of different carboxylic acids such as citric acid, malic acid, and tartaric acid on the characteristics of the nanosized GdVO4 powders was investigated. The GdVO4 powder was also synthesized without carboxylic acid for comparison. The thermal decomposition process of the car- boxylate precursors was investigated by thermogravimetric differential thermal analysis （TG-DTA）. X-ray diffraction （XRD）, Fourier transform infrared spectroscopy （FTIR）, field emission scanning electron microscope （FESEM）, transmission electron microscope （TEM）, and surface area measurement data were used to confirm the formation of nanocrystalline GdVO4 powders. It is found that the synthesis using the carboxylic acid with higher heat of combustion results in the powder with larger crystallite size. The difference in the steric effect of the acids used, which was evaluated by a computational method, also affects the degree of agglomeration of the synthesized powders.
文摘BACKGROUND： P-glycoprotein （P-gp） is a 170-kDa membrane protein. It provides a barrier function and help to excrete toxins from the body as a transporter. Some bioflavonoids have been shown to block P-gp activity. OBJECTIVE： To evaluate the important amino acid residues within nucleotide binding domain 1 （NBD l） of P-gp that play a key role in molecular interactions with flavonoids using structure-based pharmacophore model. METHODS： In the molecular docking with NBD 1 models, a putative binding site of flavonoids was proposed and compared with the site for ATP. The binding modes for ligands were achieved using LigandScout to generate the P-gp-flavonoid pharmacophore models. RESULTS： The binding pocket for flavonoids was investigated and found these inhibitors compete with the ATP for binding site in NBD1 including the NBD1 amino acid residues identified by the in silico techniques to be involved in the hydrogen bonding and van der Waals （hydrophobic） interactions with flavonoids. CONCLUSION： These flavonoids occupy with the same binding site of ATP in NBD1 proffering that they may act as an ATP competitive inhibitor.
