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A novel method for the determination of the relative stereochemistry of six-membered chairlike ring molecules by residual dipolar couplings is presented. C-H residual dipolar couplings were used to investigate the relative stereochemistry of 4,6-O-ethylidene-D-glucopyranose. For this and similar systems it is not necessary to acquire redundant dipolar couplings and to calculate the orientation order tensor. The presented methodology is a paradigmatic leap for the determination of the relative stereochemistry or remote stereochemistry in this kind of fused ring system. Residual dipolar coupling data were collected by 1D and 2D direct-measurement heteronuclear multiple quantum coherence (HMQC) spectroscopy. It was demonstrated that direct measurement of HMQC was quick and accurate for small molecules at natural abundance. [ABSTRACT FROM AUTHOR]

Examines the impact of transferred nuclear Overhauser (trNOE) on nuclear magnetic resonance diffusion measurements of ligand-protein binding. Impact of trNOE on the observed signal decay; Influence of trNOE on the measured signals of binding ligands; Use of trNOE to gain insight into ligand-protein interactions.

Aerosol pollution is a serious environmental issue, especially in China where there has been rapid urbanization. To identify the intra-annual and regional distributions of health risks and potential sources of heavy metals in atmospheric particles with an aerodynamic diameter less than or equal to 2.5 μm (PM2.5), this work collected monthly PM2.5 samples from urban, industrial, suburban, and rural areas in Nanjing city during 2016 and analyzed the heavy metal compositions (Cu, Pb, Cd, Co, V, Sr, Mn, Ti, and Sb). Enrichment factors (EFs) and principal component analysis (PCA) were applied to investigate the sources. The atmospheric PM2.5 pollution level was highest in the industrial area, followed by the urban and suburban areas, and was the lowest in the rural area. Seasonally, the concentrations of PM2.5 and associated heavy metals in spring and winter were higher than those in summer and autumn. Besides natural sources, heavy metal pollution in PM2.5 might come from metallurgical dust in the industrial area, while it mainly comes from automobile exhaust in urban and suburban areas. Health risk assessments revealed that noncancerous hazards of heavy metals in PM2.5 were low, while the lifetime cancer risks obviously exceeded the threshold. The airborne metal pollution in various functional areas of the city impacted human health differently.

Reports on diffusion-based nuclear magnetic resonance (NMR) techniques that have been incorporated into a variety of methods such as screening of chemical mixtures. Monitoring of the diffusion coefficient that enables the ligand-receptor interaction by the direct observation of the ligand signals; Characterization of the ligand epitope by the diffusion deviation.

Core-binding factors (CBFs) are a small family of heterodimeric transcription factors that play critical roles in several developmental pathways and in human disease. Mutations in CBF genes are found in leukemias, bone disorders, and gastric cancers. CBFs consist of a DNA-binding CBFα subunit (Runx1, Runx2, or Runx3) and a non-DNA-binding CBFβ subunit. CBFα binds DNA in a sequence-specific manner, whereas CBFβ enhances DNA binding by CBFα. Both DNA binding and heterodimerization with CBFβ are mediated by a single domain in the CBFα subunits known as the "Runt domain." We analyzed the energetic contribution of amino acids in the Runx1 Runt domain to heterodimerization with CBFβ. We identified two energetic "hot spots" that were also found in a similar analysis of CBFβ (Tang, Y.-Y., Shi, J., Zhang, L., Davis, A., Bravo, J., Warren, A. J., Speck, N. A., and Bushweller, J. H. (2000) J. Biol. Chem. 275, 39579-39588). The importance of the hot spot residues for Runx1 function was demonstrated in in vivo transient transfection assays. These data refine the structural analyses and further our understanding of the Runx1-CBFβ interface. [ABSTRACT FROM AUTHOR]