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Fouad FS Wright JM Plourde G Purohit AD Wyatt JK El-Shafey A Hynd G Crasto CF Lin Y Jones GB 《The Journal of organic chemistry》2005,70(24):9789-9797
[structure: see text] The viability of proteins as targets of thermally and photoactivated enediynes has been confirmed at the molecular level. Model studies using a labeled substrate confirmed the efficacy of atom transfer from diyl radicals produced from enediynes to form captodatively stabilized carbon centered aminoacyl radicals, which then undergo either fragmentation or dimerization. To exploit this finding, a family of enediynes was developed using an intramolecular coupling strategy. Derivatives were prepared and used to target specific proteins, showing good correlation between affinity and photoinduced protein degrading activity. The findings have potential applications in the design of artificial chemical proteases and add to our understanding of the mechanism of action of the clinically important enediyne antitumor antibiotics. 相似文献
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Population inversion is observed between the field independent, ground hyperfine states of 87Rb using an optical pumping technique which is applicable to a large number of species of atoms and ions. Inversion occurs upon a coherent transfer of angular momentum to the 87Rb spin system from circularly polarized light propagating in a transverse direction to a magnetic field. Coherenc is established by modulating, at certain frequencies, the light intensity or magnetic field strength. 相似文献
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Facile syntheses of pyrazole, pyridine, pyrimidine and pyrazolo[3,4-d]pyrimidine derivatives have been achieved by the reaction of β-enamino nitrile 2a with hydrazines, phenyl isothiocyanate, thiourea and active methylene reagents. The β-enamino ketone 2e with the same reagents affords 3,5-dimethyl heterocyclic ring systems. 相似文献
37.
Abbou Fouad Mohammed Chuah Hean Teik Satya Prasad Majumder 《Fiber and Integrated Optics》2013,32(2):197-206
A computer simulation of the nonlinear Schrödinger equation is carried out to evaluate the impact of nonlinear susceptibility of a single mode fiber on the transmission of a soliton pulse. The third and fifth order nonlinear susceptibilities are considered in the simulation. The results show that the output soliton pulse shape strongly depends on the third order nonlinear susceptibility and gets distorted when the full width half maximum (FWHM) pulse width is of the order of 10ps or less. 相似文献
38.
Our aim in this article is to study Noetherian and Artinian Bernstein algebras. We show that for Bernstein algebras which are either Jordan or nuclear, each of the Noetherian and Artinian conditions implies finite dimensionality. This result fails for general Noetherian or Artinian Bernstein algebras. We also investigate the relationships between the three finiteness conditions: Noetherian, Artinian, and finitely generated. Especially, we prove that Noetherian Bernstein algebras are finitely generated. 相似文献
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Miada F. Abdelwahab Tibor Kurtán Attila Mándi Werner E.G. Müller Mostafa A. Fouad Mohamed S. Kamel Zhen Liu Weaam Ebrahim Georgios Daletos Peter Proksch 《Tetrahedron letters》2018,59(27):2647-2652
Two new cryptic 3,4-dihydronaphthalen-(2H)-1-one (1-tetralone) derivatives, aspvanicin A (1) and its epimer aspvanicin B (2), as well as several known cryptic metabolites (3–8), were obtained from the ethyl acetate extract of the co-culture of the endophytic fungus Aspergillus versicolor KU258497 with the bacterium Bacillus subtilis 168 trpC2 on solid rice medium. When A. versicolor was cultured axenically in liquid Wickerham medium supplemented with 3.5% DMSO, an additional three known secondary metabolites (9–11) were isolated that were lacking when the fungus was fermented on rice medium. The structures of the new compounds were elucidated using one- and two-dimensional NMR spectroscopy as well as HRESIMS. The relative and absolute configurations of 1 and 2 were determined by the combination of NMR and electronic circular dichroism (ECD) analysis aided by DFT conformational analysis and TDDFT-ECD calculations. The ECD calculations revealed that although the sign of the blue-shifted overlapping n-π1 ECD transition follows the helicity rule of cyclic aryl ketones, the calculation of low-energy conformers and ECD spectra was necessary to determine the stereochemistry. All metabolites were assessed for their antibacterial and cytotoxic activities; one of the new diastereomers, compound 2, showed moderate cytotoxic activity against the mouse lymphoma cell line L5178Y. 相似文献