Molecular dynamics simulations of the thermal stability of tteRBP and ecRBP.

Molecular dynamics simulations were performed for investigating the thermal stability of the extremely thermophilic Thermoanaerobacter tengcongensis ribose binding protein (tteRBP) and the mesophilic homologous Escherichia coli ribose binding protein (ecRBP). The simulations for the two proteins were carried out under the room temperature (300 K) and the optimal activity temperature (tteRBP 375 K and ecRBP 329 K), respectively. The comparative analyses of the trajectories show that the two proteins have stable overall structures at the two temperatures; further analyses indicate that they both have strong side-chain interactions and different backbone flexibilities at the different temperatures. The tteRBP 375 K and ecRBP 329 K have stronger internal motion and higher flexibility than tteRBP 300 K and ecRBP 300 K, respectively, it is noted that the flexibility of tteRBP is much higher than that of ecRBP at the two temperatures. Therefore, tteRBP 375 K can adapt to high temperature due to its higher flexibility of backbone. Combining with the researches by Cuneo et al., it is concluded that the side-chain interactions and flexibility of backbone are both the key factors to maintain thermal stability of the two proteins. An animated Interactive 3D Complement (I3DC) is available in Proteopedia at http://proteopedia.org/w/Journal:JBSD:22.

Synthesis, characterization, and study on HeLa cells activity of a dinuclear complex [Cu4(phen)4(H2O)2]·(pyri)·3H2O.

The complex [Cu4(phen)4(H2O)2]·(pyri)·3H2O(where phen=1,10-phenanthroline and pyri=3,5-pyridine dicarboxylic acid)has been synthesized and characterized. IR spectra, elemental analysis and X-ray single-crystal diffraction were carried out to determine the composition and crystal structure of the complex. The binding of the complex with HC-DNA (HeLa cells DNA, which was extracted by ourselves) was investigated by fluorescence spectrum. Gel electrophoresis assay demonstrates the ability of the complex to cleave the extracted HC-DNA. Additionally, the complex exhibited a significant cytotoxic specificity and cancer cell inhibitory rate. The apoptotic tests indicate that the complex have an apoptotic effect on HeLa cells.

Synthesis, characterization, interaction with DNA and cytotoxicity in vitro of novel pyridine complexes with Zn(II).

Four novel Zn(II) complexes [Zn(L(1))(bipy)(H(2)O)(2)].4H(2)O(1), [Zn(L(1))(phen)(H(2)O)(2)].4H(2)O(2), [Zn(L(2))(bipy)(H(2)O)(2)].4H(2)O(3) and [Zn(L(2))(phen)(H(2)O)(2)].4H(2)O (4), where bipy=2,2'-bipyridine, phen=1,10-phenanthroline, L(1)=2,2'-bipyridine 5,5'-dicarboxylic acid, L(2)=2,2'-bipyridine-4,4'-dicarboxylic acid, have been synthesized and characterized using IR, (1)H NMR, element analysis and single-crystal X-ray diffractometry. The unit cell parameters for the title complex (1), a=7.9621(10)A, b=12.6853(17)A, c=13.3714(17)A, alpha=68.549(2) degrees , beta=79.065(2) degrees , gamma=88.723(2) degrees , V=1232.5(3)A(3), Z=15, space group,P-1(2).complex (4) a=9.5710(5)A, b=14.1140(7)A, c=19.0045(9)A, alpha=90 degrees , beta=99.9920(10) degrees , gamma=90 degrees , V=2528.3(2)A(3), Z=32, space group, P121/n 1(14). The binding of the complexes with fish sperm DNA (FS-DNA) was investigated by electronic absorption spectra and fluorescence spectroscopy, showing that the complexes have the ability of interaction with DNA of intercalative mode. The intrinsic binding constant K of the complexes with FS-DNA is 0.37 x 10(5)M(-1) (1) 0.73 x 10(5)M(-1) (2), 0.98 x 10(5)M(-1) (3), and 1.05 x 10(5)M(-1) (4). The results indicate that the four complexes bound to DNA with different binding affinity, in the order complex 4>3>2>1. Gel electrophoresis assay demonstrates the ability of the complexes to cleave the pBR322 plasmid DNA. The cytotoxic activity of the complexes was tested against four different cancer cell lines. The four complexes exhibited cytotoxic specificity and significant cancer cell inhibitory rate.