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91.
Nagendra Singh Ramasamy Prem Kumar Sanjit Kumar Sujata Sharma Rafia Mir Punit Kaur Alagiri Srinivasan Tej P. Singh 《Journal of molecular recognition : JMR》2009,22(6):437-445
A novel ligand‐binding site with functional implications has been identified in phospholipase A2 (PLA2). The binding of non‐steroidal anti‐inflammatory agent indomethacin at this site blocks both catalytic and anti‐coagulant actions of PLA2. A group IIA PLA2 has been isolated from Daboia russelli pulchella (Russell's viper) which is enzymatically active as well as induces a strong anti‐coagulant action. The binding studies have shown that indomethacin reduces the effects of both anti‐coagulant and pro‐inflammatory actions of PLA2. A group IIA PLA2 was co‐crystallized with indomethacin and the structure of the complex has been determined at 1.4 Å resolution. The structure determination has revealed the presence of an indomethacin molecule in the structure of PLA2 at a site which is distinct from the conventional substrate‐binding site. One of the carboxylic group oxygen atoms of indomethacin interacts with Asp 49 and His 48 through the catalytically important water molecule OW 18 while the second carboxylic oxygen atom forms an ionic interaction with the side chain of Lys 69. It is well known that the residues, His 48 and Asp 49 are essential for catalysis while Lys 69 is a part of the anti‐coagulant loop (residues, 54–77). Indomethacin binds in such a manner that it blocks the access to both, it works as a dual inhibitor for catalytic and anti‐coagulant actions of PLA2. This new binding site in PLA2 has been observed for the first time and indomethacin is the first compound that has been shown to bind at this novel site resulting in the prevention of anti‐coagulation and inflammation. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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The evolutionary history of maize (Zea mays subsp. mays) is of general interest because of its economic and scientific importance. Here we show that many cellular traits described previously in developing caryopses of maize are also seen in its wild progenitor teosinte (Zea mays subsp. parviglumis). These features, each with a possible role in development, include (1) an early programmed cell death in the maternal placento-chalazal (P-C) layer that may lead to increased hydrolytic conductance to the developing seed; (2) accumulation of phenolics and flavonoids in the P-C layer that may be related to antimicrobial activity; (3) formation of wall ingrowths in the basal endosperm transfer layer (BETL); (4) localization of cell wall invertase in the BETL, which is attributed to the increased transport capacity of photosynthates to the sink; and (5) endoreduplication in endosperm nuclei suggested to contribute to increased gene expression and greater sink capacity of the developing seed. In maize caryopsis, these cellular traits have been previously attributed to domestication and selection for larger seed size and vigor. Given the conservation of the entire cellular program in developing teosinte caryopses described here, we suggest that these traits evolved independently of domestication and predate human selection pressure. 相似文献
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Balasubramanian Radhakrishnan Radha Prasanna Pranita Jaiswal Saswati Nayak Prem Dureja 《Biologia》2009,64(5):881-889
An investigation was undertaken to evaluate a set of cyanobacterial strains in terms of production of biocidal compounds exhibiting
allelochemical and fungicidal properties. Two cyanobacterial strains — Anabaena sp. and Calothrix sp. were selected for further investigation, on the basis of their larger inhibition zones on the lawn of Synechocystis and Synechococcus sp. and two phytopathogenic fungi — Rhizoctonia bataticola and Pythium debaryanum. The diameter of the inhibition zone was largest when extracellular filtrates of the two cultures incubated at high light
intensity (90–100 μmol photons m−2 s−1) and temperature (40 ± 2 °C) or grown in medium containing two-folds higher P (1.4 mg/L, as compared to 0.7 mg/L in BG 11
medium) were taken. A pH of 8 was the most optimal for both strains, in terms of growth and biocidal activity. Partial purification
of ethyl acetate extract using TLC, followed by GLC revealed a single peak. This study highlights the importance of environmental
factors in aggravating or reducing the toxic effects of these harmful cyanobacteria and their potential as a biocontrol agent. 相似文献
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The reaction of 2-(methylthioethanol) with 1,8-dichloroanthraquinone and 1,5-dichloroanthraquinone in THF with base produces 1,8-bis(2-methylthioethoxy)anthraquinone (1) and 1,5-bis(2-methylthioethoxy)anthraquinone (2), respectively. Silver(I) complexes of 1 and 2 have been synthesized after combination with [Ag(CH3CN)4]BF4 in 1:1 M ratio to yield, [(1,8-bis(2-methylthioethoxy)anthraquinone)Ag]BF4, (3) and [(1,5-bis(2-methylthioethoxy)anthraquinone)Ag·CH3CN]BF4, (4). X-ray crystal structures of the free ligand (1) and the Ag(I) complexes (3 and 4) are reported. The intraannular carbonyl group forms a coordinate-covalent bond with Ag(I) and, in the solid state, both silver(I) complexes are found as coordination polymers. 相似文献
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