• BMB Reports
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• 제36권4호
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• pp.421-425
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• 2003

The serine/threonine protein kinase family is a large and diverse group of enzymes that are involved in the regulation of multiple cellular pathways. Elevated kinase activity has been implicated in many diseases and frequently targeted for the development of pharmacological inhibitors. Therefore, non-radioactive antibody-based kinase assays that allow high throughput screening of compound libraries have been developed. However, they require a generation of antibodies against the phosphorylated form of a specific substrate. We report here a time-resolved fluorescence assay platform that utilizes a commercially-available generic anti-phosphothreonine antibody and permits assaying kinases that are able to phosporylate threonin residues on protein substrates. Using this approach, we developed an assay for Cdc7/Dbf4 kinase activity, determined the $K_m$ for ATP, and identified rottlerin as a non-ATP competitive inhibitor of this enzyme.

• Bulletin of the Korean Chemical Society
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• 제15권3호
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• pp.249-256
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• 1994

Fluorescence time decay of human aorta has been measured at 380, 440, 480 nm using 320 nm excitation and time-correlated single photon counting technique. Fluorescence decay was found to be nonexponential at all emission frequencies. The normal and diseased sample showed significantly different fluorescence behaviors at 380 nm while this time decay difference was decreased in the fluorescence at 440 and 480 nms. The decay data were multiexponential and were analyzed with two exponential decay constants. The fluorescence decays were compared with and analyzed in terms of collagen and elastin.

• 한국가축번식학회지
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• 제16권4호
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• pp.325-333
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• 1993

A competitive type immunoassay method for 17$\beta$-estradiol(E2) based on the idiotypic anti-idiotypic antibody and time-resolved fluorescence is described. The anti-idiotypic antibody(Ab2) produced to E2 binding site of the primary idiotype antibody (Ab1) was labelled with europium and was allowed to compete with E2 standards or serum sample for the binding sites of Ab1 which was bound to 2nd antibody captured ontothe surface of microtitre plates. Fluorescence measured by time-resolved fluorometer was inversely proportional to the concentration of E2 over the range 5~500pg/well. The sensitivity of the assay was 5pg per well which was compatible with that ofradioimmunoassay using the same Ab1 and 3H-E2 as a tracer. One great advantage of this method described here was to enable antibodies to be labelled instead of haptens, and thus makes it easier to develop sensitive and robust immunoassay systems specially for haptens.

• Bulletin of the Korean Chemical Society
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• 제28권11호
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• pp.1967-1972
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• 2007

Photophysical properties of a newly-synthesized porphyrin derivative, trans-bis(ferrocene carboxylato)- (5,10,15,20-tetraphenylporphyrinato)tin(IV) [Sn(TPP)(FcCOO)2] were investigated by means of steady-state and fs-time resolved laser spectroscopic techniques, and compared with those of a standard molecule, trans-dichloro( 5,10,15,20-tetraphenyl-porphrinato)tin(IV) [Sn(TPP)Cl2]. The fluorescence spectrum of Sn(TPP)- (FcCOO)2 was observed to exhibit dual emission bands originating from the S2-state and the S1-state, which was greatly quenched as compared to those of Sn(TPP)Cl2. The fs-time resolved fluorescence and transient absorption spectroscopic measurements revealed that the fluorescence quenching is due to formation of the long-lived charge transfer state by intramolecular electron transfer from ferrocene to the S2-excited SnTPP in addition to the enhanced non-radiative deactivation processes.

• Bulletin of the Korean Chemical Society
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• 제34권2호
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• pp.465-469
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• 2013

Proton transfer reaction is one of the most fundamental processes in chemistry and life science. Excited state intramolecular proton transfer (ESIPT) has been studied as a model system of the proton transfer, since it can be conveniently initiated by light. We report ESIPT reaction dynamic of 1-hydroxy-anthraquione (1-HAQ) in solution by highly time-resolved fluorescence. ESIPT time of 1-HAQ is determined to be $45{\pm}10$ fs directly from decay of the reactant fluorescence and rise of the product fluorescence. High time resolution allows observation of the coherent vibrational wave packet motion in the excited state of the reaction product tautomer. The coherently excited vibrational mode involves large displacement of the atoms, which shortens the distance between the proton donor and the acceptor. With the theoretical analysis, we propose that the ESIPT of 1-HAQ proceeds barrierlessly with assistance of the skeletal vibration, which in turn becomes excited coherently by the ESIPT reaction.

• Journal of Photoscience
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• 제9권2호
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• pp.78-81
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• 2002

Fluorescence rise and decay curves of carotenoids were measured in solutions and in pigment protein complexes with a femtosecond time-resolved fluorescence spectroscopy. For linear carotenoids, the S$_2$ lifetimes showed the maximum value around n = 9-10. The conjugation of a keto-carbonyl group shortened the S$_2$lifetime and prolonged the S$_1$lifetime. The excitation relaxation dynamics within carotenoids and the excitation energy transfer kinetics from carotenoids to chlorophylls are discussed as a function of molecular structure of carotenoids.

• Bulletin of the Korean Chemical Society
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• 제14권1호
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• pp.72-78
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• 1993

The application of time-resolved laser induced fluorescence spectroscopy (TRLIF) to the complexation studies of Eu(III) and Cm(III) with humic substances is described. Using this method, three different spectroscopic characteristics(excitation spectra, emission spectra, and lifetimes) of these aquo ions and their complexes can be directly measured. By observing shifts in the wavelength and changes in the lifetime and intensities of the fluorescence emission, the information on the complexation behavior of humic substances with these trivalent metal cations in an aqueous solution, as well as energy transfer mechanisms, can be obtained. In addition, this method allows precise spectroscopic quantification of the complexation processes at very low concentrations of both components.

• BMB Reports
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• 제30권4호
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• pp.240-245
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• 1997

Interactions between ganglioside $G_{M3}$ and glucose transporter, GLUT1 were studied by measuring the effect of $G_{M3}$ on steady-state and time-resolved fluorescence of purified GLUT1 in synthetic lipids and on the 3-O-methylglucose uptake by human erythrocytes. The intrinsic tryptophan fluorescence showed a GLUT 1 emission maximum of 335 nm, and increased in the presence of $G_{M3}$ by 12% without shifting the emission maximum, The fluorescence lifetimes of intrinsic tryptophan on GLUT1 consisted of a long component of 7.8 ns and a short component of 2,3 ns and $G_{M3}$ increased both lifetime components. Lifetime components were quenched by acrylamide and KI. Acrylarnide-mduced quenching of long-lifetime components was partly recovered by $G_{M3}$ However. KI-induccd quenching of short- and long-lifetime components was not rescued by $G_{M3}$. The anisotropy of 1.6-diphenyl-1.3.5-hexatriene (DPH)-probed dimyristoylphosphatidylcholine (DMPC) model membrane was also increased with $G_{M3}$ incorporation, The transport rate of 3-O-methylglucose increased by 20% with $G_{M3}$ incorporation on the erythrocytes, Therefore, $G_{M3}$ altered the environment of lipid membrane and induced the conformational change of GLUT1.

• Bulletin of the Korean Chemical Society
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• 제33권3호
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• pp.993-996
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• 2012

We investigated fluorescence and fluorescence excitation of diphenylsilane (DPS) in a solution and molecular beams in combination with the aid of the DFT method. When the molecule was photoexcited at 250 nm in a cyclohexane solution, normal and excimer fluorescences were observed in the ranges of 260-320 and 330-450 nm, respectively. The fluorescence excitation spectrum indicates that the channel leading to the intramolecular excimer formation is not efficient in comparison with the normal fluorescence. Vibrationally resolved fluorescence excitation spectra were measured for the DPS molecules cooled in pulsed supersonic expansion of He in the range 262.2-271.7 nm, in which we can see several electronic excitation spectra exhibiting the electronic band origins. We found that the simulated absorption spectrum based on the time-dependent densityfunctional theory calculations accords well with the absorption spectrum.

• Bulletin of the Korean Chemical Society
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• 제12권4호
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• pp.441-444
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• 1991

The intramolecular proton transfers of 2-hydroxy-4,5-naphthotropone in room temperature solutions are studied using static and time-resolved absorption and emission spectroscopy. Dual normal and tautomer fluorescence is observed in ethanol solution, while only the tautomer fluorescence is observed in cyclohexane solution. The fluorescence lifetimes and quantum yields in ethanol and cyclohexane solutions indicate that in hydrocarbon solvents, rapid intersystem crossing competes with proton transfer in the first excited singlet state. Transient absorption spectra and kinetics indicate that proton transfer also undergoes in the first triplet state with a transfer time of ∼ 3 ns. No transient absorption from the tautomer ground state indicates a rapid back proton transfer in the ground state.