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11.
S-Adenosyl-L-homocysteine hydrolase (SAHh) inhibitors have long been used as broad-range antivirals and have been recently evaluated as an experimental therapy of filovirus infections. In response to the need for a rapid laboratory testing method that could assess antiviral potency in vivo, our group developed a capillary electrophoresis (CE) method for the determination of the S-adenosyl-L-homocysteine (SAH) to S-adenosyl-L-methionine (SAM) ratio. After chloroacetaldehyde derivatization, SAH and SAM were detected using laser-induced fluorescence detection with a HeCd laser. Separation and quantitation of both SAH and SAM in human plasma were achieved in less than 1 min. The proposed method is rapid and reliable, and could be easily applied to routine monitoring of clinical and preclinical trials subjects. 相似文献
12.
The complexation equilibria of the hydrogen salicylate ion, HL(-), have been studied, at 25 degrees C, by potentiometric measurements with a glass electrode in 1 M NaClO4 for uranyl and Nd(III) ions and in 3 M NaClO4 for Pb(II) ion. The ligand concentration (CL) was varied between 10(-3) and 0.05 M. In the system with U(VI) the concentrations ranged between: 10(-3) < or = [U(VI)] < or = 0.01 M, 0.5 < or = CL /[U(VI)] < or = 10 and 10(-2) < or = [H+] < or = 10(-5) M; for neodymium system: 2 x 10(-3) < or = [Nd(III)] < or = 0.01, 1 < or = CL /[Nd(III)] < or = 10 and 10(-2) < or = [H+] < or = 10(-7) M; for lead system: 10(-3) < or = [Pb(II) < or = 3 x 10(-3), 1 < or = CL /Pb(II)] < or = 2 and 10(-5) < or = [H+] < or = 10(-7.3) M. The experimental data have been explained with the formation of UO2HL+, UO2L, UO2(OH)L(-), (UO2)2(OH)L2(-) UO2(HL)L(-), NdHL(2+), NdL(+), Nd(OH)L, PbHL(+), PbL and PbL2(2-). Equilibrium constants are given for the investigated ionic media and at infinite dilution. 相似文献
13.
Maria Bocheska Maria Hoffmann Urszula Lesiska Emilia Luks Wanda Radecka-Paryzek 《Tetrahedron》2005,61(52):12307-12313
New compounds: 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetrakis(3-diisopropoxyphosphorylpropoxy)calix[4]arene (1) and 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetrakis(3-methoxyethoxyphosphorylpropoxy)calix[4]arene (2) were synthesized and their ionophoric properties in ion-selective membrane electrodes were studied in comparison with already described by us 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetrakis(3-diethoxyphophorylpropoxy)calix[4]arene (3). Complexes of 1 with calcium(II), lanthanum(III), europium(III) and gadolinium(III) nitrates were prepared in direct reaction of the ligand and appropriate metal salts. They were characterized by spectral data (IR, UV/Vis, luminescence, NMR, ESI-MS) and elemental analysis. The similarity in complexing behavior of the (dialkoxyphosphoryl)propoxy-calix[4]arenes toward calcium and some lanthanides was observed. 相似文献
14.
Francesco Dallavalle Emilia Fisicaro Roberto Corradini Rosangela Marchelli 《Helvetica chimica acta》1989,72(7):1479-1486
Protonation and Cu(II) complexation equilibria of L -phenyhilaninamide, N2-methyl-L-phenylalaninamide, N2, N2-dimethyl-L-phenylalaninamide, L -valinamide, and L -prolinamide have been studied by potentiometry in aqueous solution. The formation constants of the species observed, CuL2+, CuL, CuLH, CuL2H and CuL2H?2, are discussed in relation to the structures of the ligands. Possible structures of bisamidato complexes are proposed on the ground of VIS and CD spectra. Since Cu(II) complexes of the present ligands (pH range 6–8) perform chiral resolution of dansyl- and unmodified amino acids in HPLC (reversed phase), it is relevant for the investigation of the resolution mechanism to know which are the species potentially involved in the recognition process. 相似文献
15.
This paper describes a method for the detection of single-base mismatches using DNA microarrays in a format that does not require labeling of the sample ("target") DNA. The method is based on disrupting fluorescence energy transfer (FRET) between a fluorophore attached to an immobilized DNA strand ("probe") and a quencher-containing sequence that is complementary except for an artificial mismatch (e.g. 5-nitroindole, 3-nitropyrole, or abasic site) at the site of interrogation. As the displacement of the FRET acceptor and hybridization of the unlabeled probe are bimolecular, the term "bimolecular beacons" is used to describe this approach. The analysis of a mismatch was based on differences in the amount of disruption in FRET upon hybridization of perfectly matched DNA targets and those containing single-base mismatches. Using this method and an oligonucleotide model system, A/C single-base mismatches were successfully discriminated at levels greater than that observed using surface-immobilized molecular beacons. The amount of discrimination was dependent on the identity of the artificial mismatch; greater discrimination was observed with 5-nitroindole (a "universal" base) than with an abasic site. G/T mismatches, considered to be particularly difficult to detect, were also successfully discriminated when quencher sequences containing 5-nitroindole were used. 相似文献
16.
Katharine F. Bowes George Ferguson Christopher Glidewell John N. Low Antonio Quesada 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(9):o551-o554
N,N′‐Dithiobisphthalimide crystallizes from nitrobenzene solution as a solvate, 2C16H8N2O4S2·C6H5NO2, having space group Pn. The bisphthalimide molecules are linked by C—H?O hydrogen bonds and by aromatic π–π‐stacking interactions, forming a framework enclosing continuous channels running along the [100] direction and accounting for ca 20% of the unit‐cell volume. The nitrobenzene molecules lie in these channels, ordered in a head‐to‐tail fashion and linked to the bisphthalimide framework by C—H?O and C—H?π(arene) hydrogen bonds. 相似文献
17.
John N. Low Antonio Quesada Antonio Marchal Manuel Melguizo Manuel Nogueras Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(5):o289-o294
Molecules of 2‐amino‐4,6‐dimethoxypyrimidine, C6H9N3O2, (I), are linked by two N—H?N hydrogen bonds [H?N 2.23 and 2.50 Å, N?N 3.106 (2) and 3.261 (2) Å, and N—H?N 171 and 145°] into a chain of fused rings, where alternate rings are generated by centres of inversion and twofold rotation axes. Adjacent chains are linked by aromatic π–π‐stacking interactions to form a three‐dimensional framework. In 2‐benzylamino‐4,6‐bis(benzyloxy)pyrimidine, C25H23N3O2, (II), the molecules are linked into centrosymmetric R(8) dimers by paired N—H?N hydrogen bonds [H?N 2.13 Å, N?N 2.997 (2) Å and N—H?N 170°]. Molecules of 2‐amino‐4,6‐bis(N‐pyrrolidino)pyrimidine, C12H19N5, (III), are linked by two N—H?N hydrogen bonds [H?N 2.34 and 2.38 Å, N?N 3.186 (2) and 3.254 (2) Å, and N—H?N 163 and 170°] into a chain of fused rings similar to that in (I). 相似文献
18.
Angelika Wrzesiska Emilia Tomaszewska Katarzyna Ranoszek-Soliwoda Izabela Bobowska Jarosaw Grobelny Jacek Ulaski Aleksandra Wypych-Puszkarz 《Molecules (Basel, Switzerland)》2022,27(11)
At this time, the development of advanced elastic dielectric materials for use in organic devices, particularly in organic field-effect transistors, is of considerable interest to the scientific community. In the present work, flexible poly(dimethylsiloxane) (PDMS) specimens cross-linked by means of ZnCl2-bipyridine coordination with an addition of 0.001 wt. %, 0.0025 wt. %, 0.005 wt. %, 0.04 wt. %, 0.2 wt. %, and 0.4 wt. % of gold nanoparticles (AuNPs) were prepared in order to understand the effect of AuNPs on the electrical properties of the composite materials formed. The broadband dielectric spectroscopy measurements revealed one order of magnitude decrease in loss tangent, compared to the coordinated system, upon an introduction of 0.001 wt. % of AuNPs into the polymeric matrix. An introduction of AuNPs causes damping of conductivity within the low-temperature range investigated. These effects can be explained as a result of trapping the Cl− counter ions by the nanoparticles. The study has shown that even a very low concentration of AuNPs (0.001 wt. %) still brings about effective trapping of Cl− counter anions, therefore improving the dielectric properties of the investigated systems. The modification proposed reveals new perspectives for using AuNPs in polymers cross-linked by metal-ligand coordination systems. 相似文献
19.
Grzegorz Mlostoń Aneta Wróblewska Emilia Obijalska Heinz Heimgartner 《Tetrahedron: Asymmetry》2013,24(15-16):958-965
Starting with (S)-1-benzylprolinamine and α-hydroxyimino ketones, enantiomerically pure bisheterocyclic imidazole N-oxides bearing the (S)-configured N-benzyl(pyrrolidin-2-yl)methyl residue were prepared. These N-oxides reacted with 2,2,4,4-tetramethylcyclobutane-1,3-dithione to give the corresponding optically active imidazole-2-thione derivatives via a sulfur transfer reaction. Reduction of the N-oxides with Raney-nickel led to deoxygenation, whereas catalytic hydrogenation (Pd/C) in ethanol occurred with simultaneous deoxygenation and debenzylation, leading to optically active 1-(pyrrolidin-2-yl)methyl-1H-imidazoles. Alkylation of the prepared imidazole N-oxides and their respective imidazoles with butyl and hexyl bromide and subsequent anion exchange gave optically active N-alkoxy- and N-alkylimidazolium tetrafluoroborates, respectively, with the properties of ‘room temperature ionic liquids’. 相似文献