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Nine novel 1-(4'-sulfamoylphenyl)-1,2,3-triazole derivatives bearing an N-heterocycle moiety were designed using a molecular hybridisation approach and synthesised by alkyne/azide click chemistry. Most of the synthesised compounds exhibited good to moderate antiproliferative activity (IC50 values 3.7 to 77.1 µM) against stomach, oesophagus and prostate cancer cell lines, but a compound containing an S-(2-pyridyl)thiomethyl moiety showed 10-fold greater activity against the stomach cell line than 5-fluorouracil. These results demonstrate that N-heterocycle-1,2,3-triazolylsulfonamides could be promising lead compounds to develop new antitumour drugs. [ABSTRACT FROM AUTHOR]

We assessed the association between dietary intake of folate and the MTHFR genotype with breast cancer in a Chinese population, with additional analysis of the interactions of gene polymorphisms and dietary intake of folate, vitamin B, and vitamin B. A case-control study was performed, and 535 patients with newly diagnosed breast cancer and 673 controls were enrolled into this study. The MTHFR 667TT genotype (odds ratio (OR) = 1.82, 95 % confidence interval (CI) = 1.24-2.97) and T allele (OR 0= 1.48, 95 % CI = 1.15-1.78) were correlated with a moderately significant increased risk of breast cancer when compared with the CC genotype. Individuals carrying the MTR 2756GG genotype (OR = 1.66, 95 % CI = 1.16-2.56) and G allele (OR = 1.42, 95 % CI = 1.26-1.81) had a higher risk of breast cancer when compared with subjects with the AA genotype. The MTHFR 667 T allele and MTR 2756 G allele were associated with a higher risk of breast cancer in individuals with low folate intake, vitamin B, and vitamin B, but the association disappeared among subjects with moderate and high intake of folate, vitamin B, and vitamin B. This case-control study found that the MTHFR C677T and MTR A2756G polymorphisms are associated with risk of breast cancer, and folate, vitamin B, and vitamin B intakes influence these associations. [ABSTRACT FROM AUTHOR]

We theoretically investigate the effect of the δ -doping on the electron transport in a magnetic nanostructure, which can be experimentally realized by depositing one ferromagnetic stripe on the top of a semiconductor heterostructure. We find that the position and the strength of the δ -doping as well as the distance between the two magnetic fields play an important role on the electron transport properties such as the transmission probability, the conductance and the spin polarization. These interesting results may be very helpful for analyzing the spin-dependent transport mechanism of the electron and making the new types of the spintronic devices. [ABSTRACT FROM AUTHOR]

Staphylococcus aureus synthesizes polyglycerol-phosphate lipoteichoic acid (LTA) from phosphatidylglycerol. LtaS, a predicted membrane protein with 5 N-terminal transmembrane helices followed by a large extracellular part (eLtaS), is required for staphylococcal growth and LTA synthesis. Here, we report the first crystal structure of the eLtaS domain at 1.2-Å resolution and show that it assumes a sulfatase-like fold with an α/β core and a C-terminal part composed of 4 anti-parallel β-strands and a long α-helix. Overlaying eLtaS with sulfatase structures identified active site residues, which were confirmed by alanine substitution mutagenesis and in vivo enzyme function assays. The cocrystal structure with glycerolphosphate and the coordination of a Mn2+ cation allowed us to propose a reaction mechanism, whereby the active site threonine of LtaS functions as nucleophile for phosphatidyiglycerol hydrolysis and formation of a covalent threonine-glycerolphosphate intermediate. These results will aid in the development of LtaS-specific inhibitors for S. aureus and many other Gram-positive pathogens. [ABSTRACT FROM AUTHOR]

The electron paramagnetic resonance (EPR) parameters (g factors g//, g⊥ and the hyperfine structure constants) for the interstitial Co2+ center in NH4I are theoretically investigated by the diagonalization of the 6×6 energy matrix of the 4T1 ground state for a 3d7 ion under tetragonal symmetry. The contributions from the admixtures of various J (=1/2, 3/2, 5/2) states and the ligand orbital and spin-orbit coupling interactions, which were normally ignored in previous works, are taken into account in the present treatments. The contributions to the EPR parameters are discussed, and the discrepancies between the calculated hyperfine structure constants and the experimental data are also analyzed. [ABSTRACT FROM AUTHOR]

The electron paramagnetic resonance g factors and the local structure for Ni3+ in LaAl0.9Ni0.1O3 (LAN), La0.75Y0.25Al0.99Ni0.01O3 (LYAN) and YAl0.9Ni0.1O3 (YAN) are theoretically studied from the perturbation formulas of the g factors for a 3d7 ion of low spin (S = 1/2) in tetragonally elongated octahedra. In these formulas, the contributions to the g factors from the tetragonal distortion, characterized by the tetragonal field parameters Ds and Dt are taken into account. According to the calculations, the ligand octahedra around Ni3+ are suggested to suffer 2% relative elongation along the [001] (or C4) axis due to the Jahn-Teller effect. [ABSTRACT FROM AUTHOR]

Bacterial single-stranded DNA (ssDNA)-binding proteins (SSBs) play essential protective roles in genome biology by shielding ssDNA from damage and preventing spurious DNA annealing. Far from being inert, ssDNA/SSB complexes are dynamic DNA processing centers wheremany different enzymes gain access to genomic substrates by exploiting direct interactions with SSB. In all cases examined to date, the C terminus of SSB (SSB-Ct) forms the docking site for heterologous proteins. We describe the 2.7-Å-resolution crystal structure of a complex formed between a peptide comprising the SSB-Ct element and exonuclease I (ExoI) from Escherichia coil. Two SSB-Ct peptides bind to adjacent sites on ExoI. Mutagenesis studies indicate that one of these sites is important for association with the SSB-Ct peptide insolution and for SSB stimulation of ExoI activity, whereas the second has no discernable function. These studies identify a correlation between the stability of the ExoI/SSB-Ct complex and SSB-stimulation of ExoI activity. Furthermore, mutations within SSB's C terminus produce variants that fail to stimulate ExoI activity, whereas the SSB-Ct peptide alone has no effect. Together, our findings indicate that SSB stimulates ExoI by recruiting the enzyme to its substrate and provide a structural paradigm for understanding SSB's organizational role in genome maintenance. [ABSTRACT FROM AUTHOR]

With the help of the scattering-matrix method, the quantum states of ballistic electrons and conductance, as well as resistance are studied in a four-terminal junction of narrow wire with various widths. We find that these observable quantities are highly sensitive to the geometries of junctions and differ from the conventional structure with the same width. In particular, the predicted quantization conductance phenomena are striking and are also in self-consistency with calculated scattering probabilities, relating to electronic subbands and transmission states. [ABSTRACT FROM AUTHOR]

The electron paramagnetic resonance parameters, zero-field splittings (ZFSs) b02, b04, b44, b06 , b46 and the g factors for Gd3+ on the tetragonal Y3+ site in KY3F10 are theoretically studied from the superposition model for the ZFSs and the approximation formula for the g factor containing the admixture of the ground 8S7/2 and the excited 6L7/2 (L=P, D, F, G) states via the spin-orbit coupling interactions, respectively. By analysing the above ZFSs, the local structure information for the impurity Gd3+ is obtained, i.e., the impurity-ligand bonding angles related to the four-fold (C4) axis for the impurity Gd3+ center are found to be about 0.6° larger than those for the host Y3+ site in KY3F10. The calculated ZFSs based on the above angular distortion as well as the g factors are in reasonable agreement with the observed values. The present studies on the ZFSs and the local structure would be helpful to understand the optical and magnetic properties of this material with Gd dopants. [ABSTRACT FROM AUTHOR]

The local angular distortions around the impurity Co2+ in CdCl2, CdBr2 and PbI2 are theoretically studied from the perturbation formulas of the electron paramagnetic resonance (EPR) parameters, the g factors g// and g⊥ and the hyperfine structure constants A// and A⊥ for a 3d7 ion in trigonal symmetry. In these formulas, the contributions from the s-orbitals of the ligands, which were often ignored, are taken into account based on the cluster approach. By analyzing the EPR spectra, we find that the impurity-ligand bonding angles β related to the C3 axis in the Co2+ impurity centers are different from the corresponding metal-ligand bonding angles βH in the hosts, characterized by the local angular distortions Δβ (=β-βH). The calculated EPR parameters, especially the anisotropies of the g and A factors for the studied systems based on the local angular distortions Δ β, show reasonable agreement with the observed values. [ABSTRACT FROM AUTHOR]

The properties and electronic structures for boron doped bulk and monolayer AlP are studied by using the full potential linearized augmented plane-wave method. Calculations indicate, as the BP (boron substituting phosphorus), Bint (interstitial), and BAl (boron substituting aluminium) doped configurations formed, that AlP would be half-metallic ferromagnet, non-magnetic metal, and semiconductor. The band gaps for the BAl doped configurations express non-linear behaviour with varying boron compositions. Formation energies indicate that BP, BAl and BAl+BP defects could be realized experimentally. The AlP with BAl+BP defects still preserve half-metallic ferromagnetism. Monolayer AlP with BP or BAl defects still remain a semiconductor, while boron adsorbed on P or Al sites, monolayer AlP would be a non-magnetic metal. Formation energies imply that monolayer AlP with BP or BAl defects could be realized experimentally. The absorption energies indicate that boron chemically absorbs on monolayer AlP at room temperature. Our investigations indicate that boron is a promising dopant, and could be utilized to modify the AlP's properties. [ABSTRACT FROM AUTHOR]