Summary. The possibility of using synaptic plasma membrane (SPM) enzymes Na+/K+-ATPase and Mg2+-ATPase, isolated from rat brain, as a biological component of multi-response sensing system for detection of different compounds (alkaline and heavy metal salts, organic compounds) was studied. The method is based on the spectrophotometric determination of inorganic ortho-phosphate (Pi) that serves as a measure of the enzymatic activity in the presence of various analytes. The concentration of Pi, liberated by enzyme catalysed hydrolysis of adenosinetriphosphate (ATP), was followed spectrophotometrically, by single exposure to analytes or in the mixture. Pi was dose dependent on the analyte concentration. Alkaline elements (Na, K, Mg), heavy metals (Pb, Cd, Hg, Cu, Fe, Co, Zn), toxic organic compounds (pyridine, urea, chlorpyrifos), and some drugs (digoxin, gitoxin) showed diverse effects, inducing the inhibition or stimulation of the enzymes activity. Development of simple test method for simultaneous detection of the investigated analytes based on the variation of medium assay composition was discussed. 相似文献
The syn and anti isomers of cis,cis-tricyclo[5.3.0.02,6]dec-3-ene derivatives have been synthesized and their 1H and 13C NMR spectra unequivocally analyzed. Both their structures and their 1H and 13C NMR chemical shifts were calculated by DFT, the latter two calculations employing the GIAO perturbation method. Additionally, calculated NMR shielding values were partitioned into Lewis and non-Lewis contributions from the bonds and lone pairs involved in the molecules by accompanying NBO and NCS analyses. The differences between the syn and anti isomers were evaluated with respect to steric and spatial hyperconjugation interactions. 相似文献
The quantitative CE analysis of fluorine and monofluorophosphate in toothpastes is described. Separation is performed using a Waters CIA-Pak chemistry kit with Waters Electro Osmotic Flow Modifiers on a CE instrument from Spectra Physics (Spectra-phoresis 500) at elevated temperatures up to 40 °C and at a low temperature of 10 °C. The quantitative results and the simplicity are compared for the CE method, the existing standard GC procedure described in the Official Journal of the European Communities, and the procedure employing a fluoride-ion-specific electrode. 相似文献
Monolithic stationary phases for use in capillary electrochromatography were prepared by incorporation of mesoporous silica particles (of type MCM-41 or UVM-7) in a polymer obtained from butyl methacrylate and ethylene glycol dimethacrylate as monomers, 1,4-butanediol and 1-propanol as porogen, and azobisisobutyronitrile as initiator. The stability of the dispersions with varying fractions of silica particles was investigated by UV-vis spectrometry. Using continuous stirring during the capillary filling and short UV-polymerization times, polymeric beds with homogenously dispersed mesoporous particles (with contents up to 35 wt% of silica) are obtained. The resulting hybrid monolithic columns were characterized using scanning electron microscopy. The chromatographic performance of these novel stationary phases was evaluated by using alkyl benzenes and benzoic acid derivatives as test analytes. The use of these polymers leads to increased retention and separation efficiency compared to the parent monolith. The column efficiency reached values of up to 140,000 plates m?1. The resulting hybrid monolithic columns also exhibited a satisfactory reproducibility with relative standard deviations of ca. 14% (batch-to-batch).
Graphical abstract Hybrid polymer monoliths containing large amounts of mesoporous silica-particles (MCM-41 or UVM-7) were prepared by UV initiation. The prepared monolithic columns showed higher retention times and efficiencies than parent monoliths for alkyl benzenes and benzoic acid derivatives.
The expanded ligand N,N'-dimethyl-N,N'-dipyridin-2-yl-pyridin-2,6-diamine (ddpd) coordinates to copper(II) ions in a meridional fashion giving the dicationic complex mer-[Cu(ddpd)(2)](BF(4))(2) (1). In the solid state at temperatures below 100 K the cations of 1 localize in Jahn-Teller elongated CuN(6) polyhedra with the longest Cu-N bond pointing in the molecular x or y directions while the z axis is constrained by the tridentate ddpd ligand. The elongated polyhedra are ordered in an antiferrodistortive way giving an idealized zincblende structure. At higher temperature dynamically averaged (fluxional) polyhedra in the molecular x/y directions are observed by multifrequency variable temperature electron paramagnetic resonance (EPR) and by variable temperature X-ray diffraction studies. Compared to [Cu(tpy)(2)](2+) (tpy = 2,2';6',2″-terpyridine) the Jahn-Teller splitting 4δ(1) of 1 is larger. This is very probably caused by the much more favorable orbital overlap in the Cu-N bonds in 1 which results from the larger bite angle of ddpd as compared to tpy. The "freezing-in" of the Jahn-Teller dynamics of 1 (T ≈ 100 K) occurs at higher temperature than observed for [Cu(tpy)(2)](2+) (T < 77 K) which is also probably due to the larger Jahn-Teller distortion of 1 resulting in a larger activation barrier. 相似文献
Summary. Membrane-bound ATPases, such as Na,K-ATPase and nucleotide triphospho-diphosphohydrolase (NTPDase), being one of the first targets of a toxic action are generally considered as good markers for estimating toxicity. A
bioluminescence assay was applied for fast and sensitive evaluation of heavy metals effect on the rat brain synaptosomal membrane
ATPase activity. The assay consists of ATP-consuming reaction catalyzed by synaptic plasma membrane ATPases coupled to the luminescent firefly luciferase reaction, which consumes residual ATP after the course of ATPase reaction. The bioluminescence ATPase assay was applied to study the effect of heavy and transitional metals (Cu2+, Pb2+, Cd2+, Hg2+) on rat brain ATPase activity after assay optimization. All metals applied inhibited synaptic membrane ATPase activity in a concentration dependent manner. The IC50 values (Hg2+ < Cu2+ < Cd2+ < Pb2+) obtained with the bioluminescence assay were highly correlated with those obtained by the spectrophotometric method. The
fast bioluminescence ATPase assay with small sample and substrate requirements could be adjusted for high-throughput environmental and pharmacological
screening. 相似文献
The preparation of 4-(3-nitrophenyl)-2-pieoline (3) was accomplished in one step by the Zecher-Krohnke ring-closure reaction. Compound 3 is the starling material for 2-lormyl-4-(3-arninophenyl)pyridine thiosemicarbazone (4-APPT), a promising antineoplastie agent. 相似文献
A series of ten 7-quinolinediamines were prepared and evaluated for potential antiparasitic activity against P. berghei, P. cynomolgi, L. donovani and T. rhodesiense. Compounds 1d and 8 showed activity being slightly effective against L. donovani in hamsters. 相似文献
The title compounds, tetrakis(μ‐benzoato‐O:O′)bis(2,6‐diaminopyridine)‐1κN,2κN‐dicopper(II)–acetonitrile (1/2), [Cu2(C7H5O2)4(C5H7N3)2]·2C2H3N, (I), and bis(acetonitrile)‐1κN,2κN‐tetrakis(μ‐benzoato‐O:O′)dicopper(II)–acetonitrile (1/1.5), [Cu2(C7H5O2)4(C2H3N)2]·1.5C2H3N, (II), crystallize as acetonitrile solvates exhibiting different stability. They have similar molecular structures with discrete dimeric units located at crystallographic inversion centres. The copper ions are bridged by four benzoate groups and neutral N‐donor ligands, viz. 2,6‐diaminopyridine in (I) and acetonitrile in (II), are coordinated at apical positions. The diverse stability is probably due to hydrogen‐bond interactions of the solvated acetonitrile molecules with neighbouring dimers in compound (I). 相似文献
The inversion of the flexible five-membered ring in tetrahydrodicyclopentadiene (TH-DCPD) derivatives remains fast on the NMR timescale even at 103 K. Since the intramolecular exchange process could not be sufficiently slowed for spectroscopic evaluation, the conformational equilibrium is thus inaccessible by dynamic NMR. Fortunately, the spatial magnetic properties of the aryl and carbonyl groups attached to the DCPD skeleton can be employed in order to evaluate the conformational state of the system. In this context, the anisotropic effects of the functional groups in the (1)H NMR spectra prove to be the molecular response property of spatial nucleus independent chemical shifts (NICS). 相似文献