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61.
Hong Gang Hu Ming Juan Wang Qing Jie Zhao Shi Chong Yu Chao Mei Liu Qiu Ye Wu 《中国化学快报》2007,18(11):1323-1326
Protein tyrosine phosphatase 1B (PTP1B) has received considerable attention from the drug industry as a potential treatment for diabetes mellitus.Mangiferin has been reported to possess significant antidiabetic activity.Based on the previous study,eight new mangiferin derivates were synthesized and evaluated for their PTP1B inhibitory activity.Some of them displayed good inhibitory activity on PTP1B. 相似文献
62.
We herein describe the discovery of a mild, one-pot tandem acylation-cyclization for the synthesis of 4-amino-3-benzimidazol-2-ylhydroquinolin-2-ones from 2-aminobenzenecarbonitriles and ethyl 2-benzimidazol-2-yl acetates. 相似文献
63.
Dr. Himansu S. Biswal Surjendu Bhattacharyya Prof. Sanjay Wategaonkar 《Chemphyschem》2013,14(18):4165-4176
The present study combines both laser spectroscopy and ab initio calculations to investigate the intermolecular O? H???O hydrogen bonding of complexes of the tyrosine side chain model chromophore compounds phenol (PH) and para‐cresol (pCR) with H2O, MeOH, PH and pCR in the ground (S0) state as well as in the electronic excited (S1) state. All the experimental and computational findings suggest that the H‐bond strength increases in the S1 state and irrespective of the hydrogen bond acceptor used, the dispersion energy contribution to the total interaction energy is about 10–15 % higher in the S1 state compared to that in the S0 state. The alkyl‐substituted (methyl; +I effect) H‐bond acceptor forms a significantly stronger H bond both in the S0 and the S1 state compared to H2O, whereas the aryl‐substituted (phenyl; ?R effect) H‐bond donor shows a minute change in energy compared to H2O. The theoretical study emphasizes the significant role of the dispersive interactions in the case of the pCR and PH dimers, in particular the C? H???O and the C? H???π interactions between the donor and acceptor subunits in controlling the structure and the energetics of the aromatic dimers. The aromatic dimers do not follow the acid–base formalism, which states that the stronger the base, the more red‐shifted is the X? H stretching frequency, and consequently the stronger is the H‐bond strength. This is due to the significant contribution of the dispersion interaction to the total binding energy of these compounds. 相似文献
64.
High quality assays are needed in drug discovery to reduce the high attrition rate of lead compounds during primary screening. Capillary electrophoresis (CE) represents a versatile micro-separation technique for resolution of enzyme-catalyzed reactions, including substrate(s), product(s), cofactor(s) and their stereoisomers, which is needed for reliable characterization of biomolecular interactions in free solution. This review article provides a critical overview of new advances in CE for drug screening over the past five years involving biologically relevant enzymes of therapeutic interest, including transferases, hydrolases, oxidoreductases, and isomerases. The basic principles and major configurations in CE, as well as data processing methods needed for rigorous characterization of enzyme inhibition are described. New developments in functional screening of small molecules that modulate the activity of disease-related enzymes are also discussed. Although inhibition is a widely measured response in most enzyme assays, other important outcomes of ligand interactions on protein structure/function that impact the therapeutic potential of a drug will also be highlighted, such as enzyme stabilization, activation and/or catalytic uncoupling. CE offers a selective platform for drug screening that reduces false-positives while also enabling the analysis of low amounts of complex sample mixtures with minimal sample handling. 相似文献
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In this work, 0.08 mmol L−1 of phthalic acid was introduced as a mobile phase additive to quantify free amino acids (AAs) by hydrophilic interaction liquid chromatography (HILIC) coupled with electrospray ionization tandem mass spectrometry (ESI-MS/MS). The addition of phthalic acid significantly increased the signal intensity of protonated AA ions, resulting from the decrease of the relative abundance of AA sodium adducts. Meanwhile, the chromatographic peak shapes of AAs were optimized. As a consequence, there was a noticeable increase in the sensitivity of detection for AAs. The limits of detection (LOD) and quantification (LOQ) of the AAs ranged from 0.0500 to 20.0 ng mL−1 and from 0.100 to 50.0 ng mL−1, respectively, which were 4–50 times lower compared to the values measured without the addition of phthalic acid. The enhanced detection and separation of AAs were obtained by merely adding phthalic acid to the mobile phase without changing other conditions. Eventually, this simple method was validated and successfully applied to the analysis of twenty-four kinds of free AAs in human thyroid carcinoma and para-carcinoma tissues, demonstrating a significant increase of most AAs in thyroid carcinoma tissues (p < 0.05). 相似文献
67.
黄森 《中国科学B辑(英文版)》1990,(11)
The characteristics of the nigrostriatal dopaminergic neuroconnections in developing rats are studied by combined immunocytochemical and electron-microscopic techniques, with an antibody to tyrosine hydroxylase (TH). From the embryonic day 21 on, some of the THpositive nerve fibers are densely packed in the striatum to form a patch-like dopamine island. The percentage of the TH-positive nerve terminals among the labeled profiles is much higher inside than outside the dopamine island (P<0.01). On the other hand, the TH-positive terminals mainly form symmetrical axon-dendritic synapses, while most of the TH-negative terminals form asymmetrical axon-spinous synapses. The functional significance of the characterized dopaminergic connection is discussed. 相似文献
68.
G. Sivakumar K. V. Krishnamurthy J. Hao K. Y. Paek 《Chemistry of Natural Compounds》2004,40(5):499-502
Phenylalanine and tyrosine play a central role in Gloriosa superba L. calluses for the production of colchicine. The lack of biosynthetic precursors and signal inducing enzyme activity are responsible for the lower production of colchicine in vitro. B 5 medium nutrient grown calluses have a low content of colchicine, indicating that an optimal precursors level is required to increase PAL and TAL activity for colchicine accumulation. These results suggest that precursors are an important regulatory factor in colchicine accumulation in in vitro.Published in Khimiya Prirodnykh Soedinenii, No. 5, pp. 410–412, September–October, 2004. 相似文献
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Back Cover: Covalent Self‐Assembly and One‐Step Photocrosslinking of Tyrosine‐Rich Oligopeptides to Form Diverse Nanostructures (Angew. Chem. Int. Ed. 24/2016) 下载免费PDF全文