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991.
Dr. Daniele Maiolo Dr. Andrea Pizzi Dr. Alessandro Gori Dr. Lara Gazzera Dr. Nicola Demitri Dr. Alessandro Genoni Dr. Fulvio Baggi Dr. Fabio Moda Prof. Dr. Giancarlo Terraneo Prof. Dr. Francesca Baldelli Bombelli Prof. Dr. Pierangelo Metrangolo Prof. Dr. Giuseppe Resnati 《ChemistryOpen》2020,9(2):253-260
Here, we demonstrate that introduction of halogen atoms at the tyrosine 10 phenol ring of the DSGYEV sequence derived from the flexible amyloid-β N-terminus, promotes its self-assembly in the solid state. In particular, we report the crystal structures of two halogen-modified sequences, which we found to be stabilized in the solid state by halogen-mediated interactions. The structural study is corroborated by Non-Covalent Interaction (NCI) analysis. Our results prove that selective halogenation of an amino acid enhances the supramolecular organization of otherwise unstructured biologically-relevant sequences. This method may develop as a general strategy for stabilizing highly polymorphic peptide regions. 相似文献
992.
993.
Luigi Lay Francesco Nicotra Luigi Panza Giovanni Russo Guido Sello 《Journal of carbohydrate chemistry》2013,32(8):1269-1281
Abstract The use of epoxides obtained by dimethyldioxirane epoxidation of 2,3-anhydro-1,3-dideoxy-4,5:7,8-di-O-isopropylidene-D-manno-oct-1-enitol as glycosyl donors is described. This method offers a simple and stereoselective access to precursors of Kdo glycosides. The stereochemical outcome of the reaction is rationalized by means of semiempirical calculations of the transition states leading to glycosides formation. 相似文献
994.
Giuseppe Bruno Archimede Rotondo Giovanni Grassi Francesco Foti Francesco Risitano Francesco Nicol 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(7):o496-o497
The title compound, C18H15BrN2O5, a promising N‐protected α‐amino acid, was synthesized directly from an unusual bromo dipole and a 4‐(arylmethylene)oxazolone. The crystal packing of the title compound is a racemic mixture. Peculiar graph‐set motifs driven by the most important hydrogen bonds are described. 相似文献
995.
996.
997.
Luca Piemontese Salvatore Faliti Giuseppe Carbonara Antonio Laghezza Paolo Tortorella Fulvio Loiodice 《Chromatographia》2009,70(9-10):1327-1333
The LC enantiomeric separation of several dual PPARα/γ agonists on the commercially available Chiralcel OD and Chiralpak AD columns has been evaluated in normal phase mode using a mobile phase consisting in a mixture of n-hexane, 2-propanol and trifluoroacetic acid at constant volume ratio. Most compounds were separated as underivatized acids without requiring time consuming analysis. Some complementary selectivity was evidenced on the two investigated chiral stationary phases related to the different accessibility of the active sites of the helical cavities. Additional information on the chiral recognition mechanism were deduced from the chromatographic behaviour of some selected methyl esters. 相似文献
998.
Lucia Kuliková Jaromír Mikeš Martina Hýžďalová Giuseppe Palumbo Peter Fedoročko 《Photochemistry and photobiology》2010,86(6):1285-1293
Our recent study follows up an earlier one which demonstrated hypericin-mediated photocytotoxic effects on HT-29 adenocarcinoma cells by light fractionation with a longer dark pause between two unequal light doses (Sackova, A. [2005] Photochem. Photobiol. 81 , 1411–1416). Here, we present closer study on events invoked by sublethal light dose (1 J cm−2) during the period of 6 h that is sufficient to invoke resistance to second lethal dose (11 J cm−2). First, we proved that the dark pause of 6 h, but not 1 h, resulted in better cell survival with suppressed phosphatidylserine externalization, decreased reactive oxygen species production and hypericin content as well as altered expression of HSP70, GRP94, clusterin, nuclear factor (NF)-κB, IκB-α or Mcl-1. NF-κB activity assay confirmed activation of this early-response pathway. However, inhibition of IκB (IKK) kinase by parthenolide by stopping NF-κB release from the complex with IκB did not prevent onset of resistance, but it invoked some resistance even in groups with shorter, 1 h dark pause. Therefore, we predict involvement of another signaling pathway, located upstream from NF-κB, responsible for onset of resistance to photodynamic therapy with hypericin in colon adenocarcinoma cells HT-29. 相似文献
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1000.