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121.
Malihe Mohammadi Mona Atabakhshi Kashi Shekufeh Zareian Manoochehr Mirshahi Khosro Khajeh 《Applied biochemistry and biotechnology》2014,172(1):157-167
Lately it has been proposed that interaction between two positively charged side chains can stabilize the folded state of proteins. To further explore this point, we studied the effect of histidine–histidine interactions on thermostability of methylglyoxal synthase from Thermus sp. GH5 (TMGS). The crystal structure of TMGS revealed that His23, Arg22, and Phe19 are in close distance and form a surface loop. Here, two modified enzymes were produced by site-directed mutagenesis (SDM); one of them, one histidine (TMGS-HHO), and another two histidines (TMGS-HHHO) were inserted between Arg22 and His23 (HO). In comparison with the wild type, TMGS-HHO thermostability increased remarkably, whereas TMGS-HHHO was very unstable. To explore the role of His23 in the observed phenomenon, the original His23 in TMGS-HHHO was replaced with Ala (TMGS-HHA). Our data showed that the half-life of TMGS-HHA decreased in relation to the wild type. However, its half-life increased in comparison with TMGS-HHHO. These results demonstrated that histidine–histidine interactions at position 23 in TMGS-HHO probably have the main role in TMGS thermostability. 相似文献
122.
Eshtiagh-Hosseini H Housaindokht MR Beyramabadi SA Beheshti S Esmaeili AA Khoshkholgh MJ Morsali A 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,71(4):1341-1347
The new tetra dentate dianionic H2PS (N,N'-dipyridoxyl (1,3-propylenediamine)) Schiff-base ligand and its octahedral Co(III) salen complex [Co(PS)(H2O)(CH3OH)]+CH3COO(-) were synthesized, where coordinating atoms of H2PS (N,N,O(-),O(-)) occupied equatorial positions with H2O and CH3OH as axial ligands. The nature of the H2PS and its complex were determined by elemental and spectrochemical (IR, UV-vis, 1H NMR and Mass) analysis. Also, the fully optimized geometries and vibrational frequencies of them together with the 1H NMR chemical shifts of H2PS have been calculated using density functional theory (B3LYP) method. Obtained structural parameters are in good agreement with the experimental data reported for similar compounds. The calculated and experimental results confirmed the suggested structures for the ligand and complex. 相似文献
123.
A one-pot three component Biginelli condensation of different substituted aromatic and aliphatic aldehydes with ethyl acetoacetate and urea to the respective 3,4-dihydropyrimidin-2-( 1H)-ones under sol... 相似文献
124.
Maomao Xie Meng Gao Yang Yun Martin Malmsten Vincent M. Rotello Radek Zboril Omid Akhavan Aliaksandr Kraskouski John Amalraj Xiaoming Cai Jianmei Lu Huizhen Zheng Ruibin Li 《Angewandte Chemie (International ed. in English)》2023,62(17):e202217345
Antimicrobial resistance (AMR) is one of the biggest threats to the environment and health. AMR rapidly invalidates conventional antibiotics, and antimicrobial nanomaterials have been increasingly explored as alternatives. Interestingly, several antimicrobial nanomaterials show AMR-independent antimicrobial effects without detectable new resistance and have therefore been suggested to prevent AMR evolution. In contrast, some are found to trigger the evolution of AMR. Given these seemingly conflicting findings, a timely discussion of the two faces of antimicrobial nanomaterials is urgently needed. This review systematically compares the killing mechanisms and structure-activity relationships of antibiotics and antimicrobial nanomaterials. We then focus on nano-microbe interactions to elucidate the impacts of molecular initiating events on AMR evolution. Finally, we provide an outlook on future antimicrobial nanomaterials and propose design principles for the prevention of AMR evolution. 相似文献