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851.
The influences induced by various terminal substituents and solvents on the reaction mechanism and chemical dynamics of complexing ethylene with Ni dithiolene are theoretically studied by using B3LYP method and Onsager model. It is shown that the reaction should be a two-step process, and the first step is the rate-determining step. We find that the rate constant of the rate-determining step becomes small when the electron-donating ability of the substituents is increased, while it becomes large when the electron-withdrawing ability of the substituents is increased. Subsequently, we consider the solvent effects on the reaction adding ethylene to the simplified hydrogen-substituted nickel dithiolene. It is found that the solvents will make slight changes to the geometries of the reactants, transition states, intermediates and products. However, the corresponding molecular dipole moments become large with the increase of the solvent polarity, which is beneficial to accelerate the reaction. Moreover, we show that, as the solvent polarity becomes large, the activation energies of the reaction decrease exponentially, while the reaction rate constants increase exponentially. These results demonstrate that in polar solvents, the reaction complexing ethylene with Ni dithiolene may become easier and faster to occur, and the product rate is improved. We believe that this research can be seen as a reference for complex and solvent selection in olefin separation process. 相似文献
852.
Bin Feng Jin-cheng Liu Jun Zhang Ken-ichi Ozaki Yan-yan Guo Ding-hua Yi Xiao-qiang Li Ming-gao Zhao 《Molecular neurobiology》2013,47(3):892-902
Motilin is a 22-amino-acid gastrointestinal polypeptide that was first isolated from the porcine intestine. We identified that motilin receptor is highly expressed in GABAergic interneurons in the basolateral nucleus (BLA) of the amygdala, the structure of which is closely involved in assigning stress disorder and anxiety. However, little is known about the role of motilin in BLA neuronal circuits and the molecular mechanisms of stress-related anxiety. Whole-cell recordings from amygdala slices showed that motilin depolarized the interneurons and facilitated GABAergic transmission in the BLA, which is mimicked by the motilin receptor agonist, erythromycin. BLA local injection of erythromycin or motilin can reduce the anxiety-like behavior in mice after acute stress. Therefore, motilin is essential in regulating interneuron excitability and GABAergic transmission in BLA. Moreover, the anxiolytic actions of motilin can partly be explained by modulating the BLA neuronal circuits. The present data demonstrate the importance of motilin in anxiety and the development of motilin receptor non-peptide agonist as a clear target for the potential treatment of anxiety disorders. 相似文献
853.
Hongxia Zhang Yu Sun Ruimin Hu Weili Luo Xing Mao Zhonghua Zhao Qi Chen Zhigang Zhang 《Cellular signalling》2013,25(7):1574-1585
In kidney, the ubiquitin carboxy-terminal hydrolase 1 (UCH-L1) is involved in podocyte injury and proteinuria but details of the mechanism underlying its regulation are not known. Activation of NF-κB is thought to be the predominant risk factor for kidney disease; therefore, it is postulated that UCH-L1 may be one of the NF-κB target genes. In this study, we investigated the involvement of NF-κB activation in the regulation of UCH-L1 expression and the function of murine podocytes. Stimulation of podocytes with the cytokines TNF-α and IL-1β up-regulated UCH-L1 expression rapidly at the mRNA and protein levels and the NF-κB-specific inhibitor pyrrolidine dithiocarbamate resulted in down-regulation. NF-κB up-regulates UCH-L1 via binding the ? 300 bp and ? 109 bp sites of its promoter, which was confirmed by the electrophoretic mobility shift assay of DNA–nuclear protein binding. In the renal biopsy from lupus nephritis patients, the expressions of NF-κB and UCH-L1 increased in immunohistochestry staining and were positively correlated. Activation of NF-κB up-regulates UCH-L1 expression following changing of other podocytes molecules, such as nephrin and snail. These results suggest that activation of the NF-κB signaling pathway could be the major pathogenesis to up-regulate UCH-L1 in podocyte injury, followed by the turnover of other molecules, which might result in morphological changes and dysfunction of podocytes. This work help us to understand the effect of NF-κB on specific target molecules of podocytes, and suggest that targeting the NF-κB–UCH-L1 interaction could be a novel therapeutic strategy for the treatment of podocyte lesions and proteinuria. 相似文献
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856.
Xiao‐Peng Zhang Tao Wu Jian Liu Jin‐Cheng Zhao Cheng‐Hui Li Xiao‐Zeng You 《Chirality》2013,25(7):384-392
Two couples of enantiomeric platinum(II) complexes: Pt(L1a)Cl ( 1a ), Pt(L1b)Cl ( 1b ) and Pt(L1a)(C ≡ C ? Ph) ( 2a ), Pt(L1b)(C ≡ C ? Ph) ( 2b ) (L1a = (+)‐1,3‐di‐(2‐(4,5‐pinene)pyridyl)benzene, L1b = (?)‐1,3‐di‐(2‐(4,5‐pinene)pyridyl)benzene) were synthesized and characterized. Their absolute configurations were determined by single crystal X‐ray diffraction and further verified by circular dichroism (CD) spectra (including electronic circular dichroism [ECD] and vibrational circular dichroism [VCD]). These complexes show interesting mechanoluminescence and/or vapoluminescence due to crystalline‐to‐amorphous transformation. The crystalline solids, grinding‐induced amorphous powders, and vapor‐induced amorphous powders of complexes 2a and 2b were comparatively investigated by solid‐state ECD and VCD spectra. The transformation from crystalline solids to amorphous powders was accompanied by significant variances of the spectral feature in both ECD and VCD spectra. Chirality 25:384–392, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
857.
858.
The Possible Structural Models for Polyglutamine Aggregation: A Molecular Dynamics Simulations Study
Zheng-Li Zhou Jian-Hua Zhao Hsuan-Liang Liu Josephine W. Wu Kung-Tien Liu Chih-Kuang Chuang 《Journal of biomolecular structure & dynamics》2013,31(5):743-758
Abstract Huntington's disease is a neurodegenerative disorder caused by a polyglutamine (polyQ) expansion near the N-terminus of huntingtin. Previous studies have suggested that polyQ aggregation occurs only when the number of glutamine (Q) residues is more than 36-40, the disease threshold. However, the structural characteristics of polyQ nucleation in the very early stage of aggregation still remain elusive. In this study, we designed 18 simulation trials to determine the possible structural models for polyQ nucleation and aggregation with various shapes and sizes of initial β-helical structures, such as left-handed circular, right-handed rectangular, and left- and right-handed triangular. Our results show that the stability of these models significantly increases with increasing the number of rungs, while it is rather insensitive to the number of Qs in each rung. In particular, the 3-rung β-helical models are stable when they adopt the left-handed triangular and right-handed rectangular conformations due to the fact that they preserve high β-turn and β-sheet contents, respectively, during the simulation courses. Thus, we suggested that these two stable β-helical structures with at least 3 rungs might serve as the possible nucleation seeds for polyQ depending on how the structural elements of β-turn and β-sheet are sampled and preserved during the very early stage of aggregation. 相似文献
859.
860.
Guo-qing Song Aaron Walworth Dongyan Zhao Ning Jiang James F. Hancock 《Plant cell reports》2013,32(11):1759-1769