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111.
Acyclic and cyclic unsaturated carboxylic acids 1 to 4 are most easily converted to unsaturated dicarboxylic acids 5 to 8 by oxidative coupling of their diene- or triene-diolates by 1,2-diiodoethane. This procedure improves formerly reported oxidations by iodine or silver salts. 相似文献
112.
Francis DM Różycki B Tortajada A Hummer G Peti W Page R 《Journal of the American Chemical Society》2011,133(43):17138-17141
The MAP kinase ERK2 (ERK2, extracellular signal-regulated kinase 2) is regulated by numerous phosphatases that tightly control its activity. For example, the hematopoietic tyrosine phosphatase (HePTP) negatively regulates T cell activation in lymphocytes via ERK2 dephosphorylation. However, only very limited structural information is available for these biologically important complexes. Here, we use small-angle X-ray scattering combined with EROS ensemble refinement to characterize the structures of the resting and active states of ERK2:HePTP complexes. Our data show that the resting state ERK2:HePTP complex adopts a highly extended, dynamic conformation that becomes compact and ordered in the active state complex. This work experimentally demonstrates that these complexes undergo significant dynamic structural changes in solution and provides the first structural insight into an active state MAPK complex. 相似文献
113.
J. -P. Morizur B. Desmazières J. Chamot-Rooke V. Haldys P. Fordham J. Tortajada 《Journal of the American Society for Mass Spectrometry》1998,9(7):731-734
The use of copper ions for chemical ionization (CI) coupled with gas chromatography/mass spectrometry (GC/MS) of hydrocarbons is reported. Cu+?CI was performed in a high-pressure, fast atom bombardment ion source coupled with both a gas chromatograph and a mass spectrometer. The suitability of the Cu+?CI method is illustrated by the analysis of pure alkylbenzenes, alkylthiophenes, octenes, and by the analysis of a light mixture of aromatic hydrocarbons. The Cu+?CI/GC mass spectra display an abundant [M+63Cu]+ ion, together with fragmentations, that are of structural interest. The detection limit for isobutylbenzene, taken as model compound, is 100 times lower than that for electron ionization. 相似文献
114.
Petrova A Davids LM Rautenbach F Marnewick JL 《Journal of photochemistry and photobiology. B, Biology》2011,103(2):126-139
The possible mechanism of photoprotection by polyphenolic extracts of honeybush and the two most abundant polyphenols found in honeybush, hesperidin and mangiferin were determined using a mouse model. Ethanol: acetone soluble extracts and pure honeybush compounds were applied topically to the skin of SKH-1 mice before daily exposures to ultraviolet B (UVB) (180 mJ/cm2) for 10 days. The honeybush extracts reduced signs of sunburn, such as erythema, peeling and hardening of the skin and also significantly (P < 0.05) reduced edema, epidermal hyperplasia and the induction of cyclooxygenase-2 (COX-2), ornithine decarboxylase (ODC), GADD45 and OGG1/2 expression. The fermented honeybush extract significantly (P < 0.05) reduced lipid peroxidation and depletion of the antioxidant enzymes catalase and superoxide dismutase. Hesperidin and mangiferin were less effective. These results show that extracts of honeybush and to some extent, hesperidin and mangiferin, renders protection against UVB-induced skin damage. The mechanisms investigated suggest that honeybush extracts protected the skin via modulation of induced-oxidative damage, inflammation and cell proliferation. Other specific biological properties such as modulation of signaling pathways could also be involved. 相似文献
115.
Lamsabhi AM Mó O Yáñez M Salpin JY Haldys V Tortajada J Guillemin JC 《The journal of physical chemistry. A》2008,112(42):10509-10515
The reaction of aminoacrylonitrile, a species of astrochemical interest, with Ni(+)((2)D(5/2)) was investigated by means of mass spectrometry techniques and density functional theory calculations. The dominant fragmentations in the MIKE spectrum correspond to the loss of [C2,N,H3], HCN, and NH3, the loss of H2 being very minor. The structure and bonding of the different aminoacrylonitrile-Ni(+) complexes were investigated at the B3LYP/6-311G(d,p) level of theory. The same approach was employed in our survey of the corresponding potential energy surface. This survey indicates that the [C2,N,H3] neutral product can be formed either as ketenimine (CH2CNH) or acetonitrile. The formation of the latter is significantly more exothermic but involves slightly higher activation barriers; so very likely, both isomers are produced along the reaction process. The lost of HNC is not competitive with the loss of HCN, because when the former is formed the products lie higher in energy and the corresponding mechanisms involve energy barriers above the entrance channel. The loss of NH3 is associated with the formation of a complex between cyanoacetylene, HCCCN, which is very abundant in the interstellar media, and Ni(+). 相似文献
116.
Regioselective reaction of lithium diene-and triene-diolates 1 and 2 with O-diphenylphosphinyl hydroxylamine affords unsaturated α-amino acids 3 and 4. Addition to DEAD leads selectively to γ-hydrazino unsaturated acids 5 and 6. 相似文献
117.
118.
Faure K Fujimoto J Shimabukuro DW Ajayi T Shime N Moriyama K Spack EG Wiener-Kronish JP Sawa T 《Journal of immune based therapies and vaccines》2003,1(1):2