• KSBB Journal
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• v.22 no.1
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• pp.48-52
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• 2007

This study was carried out to establish the optimum disruption condition of a sonificator for the protein toxin for the purpose of developing automatic biological agent detector equipped a sonificator. One of the best-known collisional quenchers is molecular oxygen, which quenches almost all known fluorophores. The sonification does an excellent job of degassing, which decreased the quenching effect and increased the fluorescence quantity. The fluorescence measurement for the protein using 0.7 X fluorescent dye concentration and above must be done in 1 minute and the fluorescence measurement for the protein using 0.3 X fluorescent dye concentration and below has to be done between 2 and 3 minute. The fluorescence quantity of the sonificatied protein sample was much higher that of the non-sonificatied protein sample. Sonificating the sample turned out to be favorable for the fluorescence measurement when measuring at the low protein concentration.

• Journal of Plant Biology
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• v.34 no.4
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• pp.303-309
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• 1991

Limitation of photosynthesis in detached Chinese cabbage (Brassica campestris L.) leaves was induced by feeding of mannose (25 mM) for 12 h in the light, and changes in the basic thylakoid functions under this condition were investigated. The acid soluble phosphate contend and CO2 uptake rate was decreased by 66% and 67%, respectively. However, the starch content was increased by 24% compared to those of controls. From the fast induction curves of chlorophyll fluorescence, dark level fluorescence (Fo) slightly increased while intermediate plateau fluorescence level (FI) to peak level fluorescence (Fp) transient was significantly decreased with a slight decrease in the Fo-to-FI transient. This data means that reduction of secondary electron acceptor of PSII (QB) might be more severely inhibited than that of primary electron acceptor of PSII (QA) by decrease in phosphate level. The strong decline of (Fv)m//Fm ratio suggests that efficiency of excitation energy capture by PSII was decreased markedly. The quenching of Fo (qO), an indicator of state transition, was also occurred over the slow induction kinetics of chlorophyll fluorescence. From quenching analysis, fluorescence was dominantly quenched by nonphotochemical quenchings (qE+qT). These results showed that the capture and transfer efficiency of excitation energy to PSII reaction center in thylakoid was decreased with the decline of leaf phosphate level, and that the state transition was occurred during the induction of photosynthesis under these conditions.

• Bulletin of the Korean Chemical Society
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• v.32 no.8
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• pp.2599-2606
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• 2011

The fluorescence of ethidium bound to DNA, poly[d(A-T)$_2$], and poly[d(G-C)$_2$] at a [ethidium]/[DNA] ratio of 0.005 was quenched by porphyrins when both ethidium and the porphyrins simultaneously bound to the same polynucleotide. The quenching was tested using the "inner sphere" and the "Forster resonance energy transfer" (FRET) models, with the latter found to contribute, at least in part, to the quenching. Meso-tetrakis(N-methylpyridinium-4-yl)porphyrin (TMPyP) exhibited a higher quenching and FRET efficiency than cis-bis(N-methylpyridinium-4-yl)porphyrin (BMPyP) for all of the tested DNA and polynucleotides, demonstrating that energy transfer efficiency is affected by the number of positive charges of porphyrins.

• Bulletin of the Korean Chemical Society
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• v.33 no.2
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• pp.529-534
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• 2012

The fluorescence of 4',6-diamidino-2-phenylindole (DAPI) bound to DNA at a [DAPI]/[DNA base] ratio of 0.005 was quenched by meso-tetrakis(N-methylpyridinium-4-yl)porphyrin (TMPyP) or cis-bis(N-methylpyridinium-4-yl)porphyrin (BMPyP) when both DAPI and either porphyrin spontaneously bound to the same DNA strand. The quenching was investigated using the "one-dimensional inner sphere" and the "F$\ddot{o}$rster resonance energy transfer" (FRET) models. Total quenching occurred when DAPI and TMPyP were up to 19.3 base pairs or $66\AA$ apart. BMPyP could quench the fluorescence up to 13.9 base pairs or $47\AA$. TMPyP, which intercalated between the DNA base-pairs, appeared to be a better acceptor than BMPyP, which stacked along the DNA stem. The higher quenching and higher resonance energy transfer efficiency of TMPyP was due to the larger overlap integral between its absorption spectrum and the emission spectrum of DNA-bound DAPI.

• Bulletin of the Korean Chemical Society
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• v.29 no.8
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• pp.1510-1518
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• 2008

Results of intrinsic and extrinsic fluorescence studies on choline oxidase revealed that the enzyme at high alkaline pH values has more accessible hydrophobic patches relative to acidic pH. Fluorescence quenching studies with acrylamide confirm these changes. The quenching constants were also determined at different pH(s) by using the Stern-Volmer equation. CD studies showed that at higher pH a transition from $\alpha$-helix to $\beta$- structure was appeared while at lower pH the content of $\alpha$-helix structure was increased. Furthermore, analysis of the spectral data using chemometric method gave evidence for existence of intermediate components at very high pH(s). Results of thermal denaturation evaluated that the enzyme has the most instability at higher pH(s). Altogether low and high pH values caused significant alteration on secondary and tertiary structures of choline oxidase via inducing of an intermediate.

• Journal of Photoscience
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• v.1 no.1
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• pp.47-52
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• 1994

Effects of HgCl$_2$-treatment on electron transport, chlorophyll a fluorescence and its quenching were studied using isolated barley (Hordeum vulgare L. cv. Albori) chloroplasts. Depending on the concentration of HgCI$_2$, photosynthetic oxygen-evolving activities of photosystem II (PS II) were greatly inhibited, whereas those of photosystem I (PS I) were slightly decreased. The inhibitory effects of HgCl$_2$ on the oxygen-evolving activity was partially restored by the addition of hydroxyamine, suggesting the primary inhibition site by HgCl$_2$2-treatment is close to the oxidizing site of PS tl associated with water-splitting complex. Addition of 50 $\mu$M HgCI$_2$ decreased both photochemical and nonphotochemical quenching of chlorophyll fluorescence. Especially, energy dependent quenching (qE) was completely disappeared by HgCl$_2$-treatment as observed by NH$_4$CI treatment. In the presence of HgCI$_2$, F'o level during illumination was also increased. These results suggest that pH gradient across thylakoid membrane can not be formed in the presence of 0 $\mu$M HgCl$_2$. In addition, antenna pigment composition might be altered by HgCl$_2$-treatment.

• Bulletin of the Korean Chemical Society
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• v.15 no.8
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• pp.663-669
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• 1994

Decay kinetics of Ga(5s), Ga(5p) and Ga(4d) atoms in Ar were studied by laser induced fluorescence technique. Theground state gallium atoms in the gas phase were generated by pulsed dc discharge of trimethyl gallium and argon mixtures. Both pulsed discharge and YAG-DYE laser system were controlled by a dual channel pulse generator and the delay time between the end of discharge and laser pulses was set 3.0-6.0 ms. The Ga(5s) and Ga(4d) atoms were generated by single photon excitation from the ground state Ga atoms and radiative lifetimes as well as the total quenching rate constants in Ar were obtained from the pressure dependence of the fluorescence decay rates. The Ga(5p) atoms were populated by a two-photon excitation method and the cascade fluorescence from Ga(5s) atoms were analyzed to extract quenching rate constant of Ga(5p) atoms by Ar in addition to radiative lifetimes of Ga(5p) state. The magnitudes of the quenching rate constants by Ar for the low-lying excited states of Ga atoms are 1.6-3$ {\times}10^{-11}cm^3$ molecul$e^{-1}s^{-1}$, which are much larger than those for alkali, alkaline earth and Group 12 metals. Based on the measured rate constants, kinetic simulations were done to assign state-to-state rate constants.

• BMB Reports
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• v.30 no.4
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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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• v.8 no.1
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• pp.27-30
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• 1987

Photocycloaddition of 1,4,5,8-tetraazaphenanthrene to olefins proceeds through a biradical triplet-state intermediate as proven by the photoproduct stereochemistry, quantum yield measurements, sensitization, quenching, and fluorescence and phosphorescence quenching studies.

• Journal of Environmental Science International
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• v.5 no.4
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• pp.545-553
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• 1996

The effects of 0.2 ppm ozone on the developing chloroplast of barley (Hordeum vulgare L.) seedling during greening were examined by chlorophyll contents, photosynthetic electron tiansport activity, Fo, Fv and fluorescence quenching coefficient. Chlorophyll contents of seedling treated with ozone were not changed in comparison with the control during the 96 h greening experiment, but PS II activity of the chloroplasts of seedlings treated with ozone was decreases by- l5%. Fo was slightly decreased but Fv was decreases by 5% in comparison with the control, In fluorescence quenching analysis, qP and qE were decreased by 11% and 9%, respectively, in comparison with the control. These results suggest that oxidation site of PS II is the site affected mostly and PQ pool is also affected slightly by 0.2 ppm ozone.