A quinoline-based Cu2+ ion complex fluorescence probe for selective detection of inorganic phosphate anion in aqueous solution and its application to living cells.

A quinaldine functionalized probe QP has been designed and synthesized. It exhibited selective turn-off fluorescence response toward Cu2+ ion over most of the biologically important ions at physiological pH. The binding ratio of the probe QP and Cu2+ ion was determined to be 1:1 through fluorescence titration, Job's plot and ESI-MS. The binding constant (K) of Cu2+ to probe QP was found to be 2.12×104M-1. Further, the Cu2+ ensemble of probe QP was found to respond H2PO4- and HPO42- among other important biological anions via fluorescence turn-on response at physiological pH. Fluorescence microscopy imaging using living Hela cells showed that probe QP could be used as an effective fluorescent probe for detecting Cu2+ cation and H2PO4- and HPO42- anions in living cells.

Ab initio, density functional theory and structural studies of 4-amino-2-methylquinoline.

The Fourier transform infrared (FTIR) and FT-Raman spectra of 4-amino-2-methylquinoline (AMQ) have been recorded in the range 4000-400 and 4000-100 cm(-1), respectively. The experimental vibrational frequency was compared with the wavenumbers obtained theoretically by ab initio HF and DFT-B3LYP gradient calculations employing the standard 6-31 G** and high level 6-311 ++G** basis sets for optimised geometry of the compound. The complete vibrational assignment and analysis of the fundamental modes of the compounds were carried out using the experimental FTIR and FT-Raman data, and quantum mechanical studies. The geometry and normal modes of vibration obtained from the HF and DFT methods are in good agreement with the experimental data. The potential energy distribution of the fundamental modes was calculated with ab initio force fields utilising Wilson's FG matrix method. The NH-pi interactions and the influence of amino and methyl groups on the skeletal modes are investigated.

A fluorometric assay for the determination of 1-deoxy-D-xylulose 5-phosphate synthase activity.

We report a novel fluorometric end-point assay for the determination of 1-deoxy-d-xylulose 5-phosphate synthase (DXS) activity based on the reaction of 1-deoxy-D-xylulose 5-phosphate (DX5P) with 3,5-diaminobenzoic acid in an acidic medium to form a highly fluorescent quinaldine derivative. The assay was validated in three ways: (a) for a fixed amount of DXS in the reaction mixture the emitted fluorescence increased linearly with the reaction time, (b) for a fixed reaction time fluorescence intensity increased with the concentration of DXS in the reaction mixture, and (c) the increase in fluorescence intensity correlated (r = 0.99; P < 0.002) with the amount of DX5P formed in the reaction mixture determined radiometrically. The sensitivity of the fluorometric assay is similar to that of the previously described radiometric methods. This assay can be useful for the functional characterization of DXS as well as for the screening of DXS inhibitors with potential antibiotic, herbicidal, or antimalarial action.

Quinoline and methylquinolines in cigarette smoke: comparative data and the effect of filtration.

A method has been developed to determine quantitatively quinoline, isoquinoline, and each of the methylquinoline isomers in cigarette smoke. This method was applied to the smoke of several different commercial cigarettes with and without filter tips. Quantitative analyses were accomplished by capillary gas chromatography, using a 50-m OV-101 fused silica capillary column and a 50-m Dexsil 300 fused silica column. Quinoline, isoquinoline and all seven of the methylquinolines were found in cigarette smoke. When cigarettes were analyzed with and without filter tips, these compounds were reduced by filtration, but not as much as tar was reduced. The significance of these data is discussed in view of the biological activity of specific isomers of these environmental pollutants.