Search results for "Fluorescence"
showing 10 items of 2463 documents
Design and Synthesis of Novel 1,3-Thiazole and 2-Hydrazinyl-1,3-Thiazole Derivatives as Anti-Candida Agents: In Vitro Antifungal Screening, Molecular…
2019
In the context of there being a limited number of clinically approved drugs for the treatment of Candida sp.-based infections, along with the rapid development of resistance to the existing antifungals, two novel series of 4-phenyl-1,3-thiazole and 2-hydrazinyl-4-phenyl-1,3-thiazole derivatives were synthesized and tested in vitro for their anti-Candida potential. Two compounds (7a and 7e) showed promising inhibitory activity against the pathogenic C. albicans strain, exhibiting substantially lower MIC values (7.81 &mu
A multicommutated flow system for determination of bismuth in milk shakes by hydride generation atomic fluorescence spectrometry incorporating on-lin…
2004
Abstract A highly sensitive method was developed for determination of bismuth in milk shakes by multicommutation hydride generation atomic fluorescence spectrometry (HG-AFS) based on off-line sonication for 10 min with aqua regia 8% (v/v) and on-line waste treatment. The instrumentation and chemistry variables were studied in order to provide the best performance. The limit of detection in the original samples, established for a probability level of 99.6% (k = 3), was 1.67 ng/g Bi. The method provides a fast alternative in control analysis with a sampling throughput of 72 h as compared with 31 h obtained by the classical continuous measurement. Additionally, multicommutation reduces waste g…
Fluorescence-based assays for screening nine cytochrome P450 (P450) activities in intact cells expressing individual human P450 enzymes.
2004
In this study we describe a battery of fluorescence assays for rapid measurement in intact cells of the activity of nine cytochromes P450 (P450s) involved in drug metabolism. The assays are based on the direct incubation of monolayers of cells expressing individual P450 enzymes with a fluorogenic substrate followed by fluorimetric quantification of the product formed and released into incubation medium. For each individual P450 activity, different fluorescence probes were examined, and the one showing the best properties (highest metabolic rates, lowest background fluorescence) was selected: 3-cyano-7-ethoxycoumarin for CYP1A2 and CYP2C19, coumarin for CYP2A6, 7-ethoxy-4-trifluoromethylcoum…
Hydrolytic action of phospholipase A2 in monolayers in the phase transition region: direct observation of enzyme domain formation using fluorescence …
1990
Phospholipase A2, a ubiquitous lipolytic enzyme highly active in the hydrolysis of organized phospholipid substrates, has been characterized optically in its action against a variety of phospholipid monolayers using fluorescence microscopy. By labeling the enzyme with a fluorescent marker and introducing it into the subphase of a Langmuir film balance, the hydrolysis of lipid monolayers in their liquid-solid phase transition region could be directly observed with the assistance of an epifluorescence microscope. Visual observation of hydrolysis of different phospholipid monolayers in the phase transition region in real-time could differentiate various mechanisms of hydrolytic action against …
Unusual phosphine oxidation: new triazolopyridyl-quinolyl phosphine oxide fluorescent dyes
2015
3-(2-Pyridyl)-[1,2,3]triazolo[1,5-a]quinolylphosphines suffer an unusual phosphine oxidation due to their special geometry that allows a s-donation of the nitrogen (N1) lone pair to phosphorus. This family of compounds behaves as strong fluorophores with high quantum yields.
Differential gene expression in p53-mediated G(1) arrest of human fibroblasts after gamma-irradiation or N-phosphoacetyl-L-aspartate treatment.
2000
In human fibroblasts, N:-phosphoacetyl-L-aspartate (PALA) and gamma-radiation induce reversible and irreversible p53-mediated G(1) cell cycle arrest, respectively. By coupling the premature chromosome condensation technique to fluorescence in situ hybridization, we found no evidence of DNA damage after PALA treatment. We used representational difference analysis (cDNA-RDA) to study changes in gene expression after PALA treatment and gamma-radiation in normal human fibroblasts. The mammary-derived growth inhibitor (MDGI) gene was expressed in PALA-treated cells. Ectopic MDGI expression arrested PALA-treated but not irradiated RKO cells. Expression of an antisense RNA against MDGI resulted in…
Conformational relaxation of a low-temperature protein as probed by photochemical hole burning. Horseradish peroxidase
1991
For the first time, conformational relaxation processes have been measured in a small protein, mesoporphyrin-horseradish peroxidase via their influence on spectral diffusion broadening of holes burnt in the fluorescence excitation spectrum of free base mesoporphyrin. Holes were burnt in three 0----0 bands of different tautomeric forms of the chromophore at 1.5 and 4 K, and the spectral diffusion broadening was measured in temperature cycling experiments between 4 and 30 K. The inhomogeneous linewidth for the tautomeric 0----0 bands was estimated to be 60-70 cm-1; the hole width was found narrow, being in the order of 350 MHz (10(-2) cm-1) at 1.5 K what allowed for an extremely sensitive det…
Photochemistry of 1,2,4-oxadiazoles. A DFT study on photoinduced competitive rearrangements of 3-amino- and 3-N-methylamino-5-perfluoroalkyl-1,2,4-ox…
2006
The photoinduced competitive rearrangements of 5-perfluoroalkyl-3-amino(N-alkylamino)-1,2,4-oxadia- zoles have been investigated by DFT calculations and UV-vis spectroscopy. The observed product selectivity depends on the number of hydrogen atoms present in the amino moiety and involves two or three possible routes: (i) ring contraction-ring expansion (RCRE), (ii) internal-cyclization isomerization (ICI), or (iii) C(3)-N(2) migration-nucleophilic attack-cyclization (MNAC). UV absorption and fluorescence spectra of the reactants, and vertical excitation energy values, calculated by time dependent DFT, support the involvement of a neutral singlet excited state in the photoexcitation process. …
Solid-Phase Synthesis of Peptide Libraries Combining α-Amino Acids with Inorganic and Organic Chromophores
2009
The synthesis of two series of peptidic chains composed of bis(terpyridine)ruthenium(II) acceptor units and organic chromophores (coumarin, naphthalene, anthracene, fluorene) by stepwise solid-phase peptide synthesis (SPPS) techniques is described. The first series of dyads comprises directly amide linked chromophores, while the second one possesses a glycine spacer between the two chromophores. All dyads were studied by UV/Vis and NMR spectroscopy, steady-state luminescence, luminescence decay and electrochemistry, as well as by DFT calculations. The results of these studies indicate weak electronic coupling of the chromophores in the ground state. Absorption spectra of all dyads are domin…
Properties of baculovirus particles displaying GFP analyzed by fluorescence correlation spectroscopy.
2003
Abstract Recombinant baculovirus particles displaying green fluorescent protein (GFP) fused to the major envelope glycoprotein gp64 of the Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) were characterized by fluorescence correlation spectroscopy (FCS). FCS detected Brownian motion of single, intact recombinant baculovirus display particles with a diffusion coefficient (D) of (2.89±0.74)10 8 cm2s 1 and an apparent hydrodynamic radius of 83.35±21.22 nm. In the presence of sodium dodecyl sulfate (SDS), Triton X-100, and octylglucoside, the diffusion time was reduced to the 0.2 ms range (D = 7.5710 7 cm2s 1), showing that the fusion proteins were anchored in the viral envelope…