• 약학회지
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• 제20권3호
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• pp.130-137
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• 1976

Specific association phenomena of riboflayin-2',3',4',5',- tetraacetate and salicylic acid derivatives, such as salicylic acid, aspirin and salicylamide have been measured by infrared and fluorescence spectroscopy. Salicylic acid and riboflavin tetraacetate oxyl group of the former. Asprin and riboflavin tetraacetate form the 1:1 cyclic hydrogen bonded dimer by the same mode. Salicylamide froms the 1:1 cyclic hydrogen bonded dimer with riboflavin tetraacetate by using its amide group and carbonyl group. Salicylic acid derivatives are effective quenchers of the fluorescence of riboflavin tetraacetate. It is appeared that salifylamide is the strongest quencher among them. The quenching effect is attributed to the formation of association dimer.

• Rapid Communication in Photoscience
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• 제3권4호
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• pp.79-80
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• 2014

We characterized the one-electron reduction of oligodeoxynucleotides with a 2-oxopropyl group on a thymine base ($d^{oxo}T$) and applied the reaction to the radiolytic activation of DNAzyme function. We designed a system in which the DNAzyme function of cleaving mRNA was suppressed by introduction of $d^{oxo}T$ into the strand of DNAzyme. Hypoxic X-irradiation led to recovery of the cleavage ability because the 2-oxopropyl group was removed to form unmodified DNAzyme. We characterized the DNAzyme function by monitoring the fluorescence change of fluorophore- and quencher-labeled target strands. We confirmed that the DNAzyme function could be regulated by hypoxic X-irradiation and the reaction of $d^{oxo}T$.

• Journal of Microbiology and Biotechnology
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• 제16권6호
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• pp.821-831
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• 2006

Unicellular green algae of the genus Haematococcus have been studied extensively as model organisms for secondary carotenoid accumulation. Upon environmental stress, such as strong irradiance or nitrogen deficiency, unicellular green algae of the genus Haematococcus accumulate secondary carotenoids in vesicles in the cytosol. Because secondary carotenoid accumulation occurs only upon specific environmental stimuli, there is speculation about the regulation of the biosynthetic pathway specific for secondary carotenogenesis. Because the carotenoid biosynthesis pathway is located both in the chloroplast and the cytosol, communication between both cellular compartments must be considered. Recently, the induction and regulation of astaxanthin biosynthesis in microalgae received considerable attention because of the increasing use of this secondary carotenoid as a source of pigmentation for fish aquaculture, as a component in cancer prevention, and as a free-radical quencher. This review summarizes the biosynthesis and regulation of the pathway, as well as the biotechnology of astaxanthin production in Haematococcus.

• Bulletin of the Korean Chemical Society
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• 제32권9호
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• pp.3229-3232
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• 2011

A FRET-based high-throughput screening system was developed for the discovery of competitive smallmolecule Hsp90 inhibitors. The biarsenical fluorescein derivative FlAsH and dabcyl-conjugated Hsp90 inhibitor GM were employed as the FRET donor and quencher, respectively. The spatial proximity perturbation between FlAsH-labeled Hsp90N and GM-dabcyl upon treatment of a small molecule led to changes in the FRET-induced fluorescence, monitored in a high-throughput fashion.

• Bulletin of the Korean Chemical Society
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• 제26권3호
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• pp.413-417
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• 2005

Fluorescence of green fluorescent protein mutant, 2-5 GFP is observed during denaturation by guanidine. The fluorescence intensity decreases exponentially but the fluorescence lifetime does not change during denaturation. The fluorescence lifetime of the denatured protein is shorter than that of native form. As the protein structure is modified by guanidine, solvent water molecules penetrate into the protein barrel and protonate the chromophore to quench fluorescence. Most fluorescence quenchers do not affect the fluorescence of native form but accelerate the fluorescence intensity decay during denaturation. Based on the observations, a simple model is suggested for the structural change of the protein molecule during denaturation.

• Nuclear Engineering and Technology
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• 제33권2호
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• pp.166-174
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• 2001

An apparatus for detecting remote real-time uranium concentration using an optrode was developed. An optrode to detect uranium fluorescence as remote real-time control was designed. Fluorescence intensity at time 2ero was derived by the fluorescence signal processing and the algorithm to exclude the quenching effect of various quenchers and temperature fluctuations. This apparatus employing the above deriving method and the optrode has an error range within 6% in spite of serious fluorescence lifetime changes due to the quenching effect and temperature fluctuations. The detection limit is 0.06 ppm and the linearity is excellent between 0.06 ppm and 2 ppm on the aqueous uranium solution.

• 대한화장품학회지
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• 제10권1호
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• pp.75-89
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• 1984

$^1O_2$ quenching abilities of several carotenoids which contain hydroxy, carbonyl and ester groups were compared quantitatively with $\beta$-carotene, and the capacity of the quenching was interpreted in the light of electronic effects. The rate constans of $^1O_2$ quenching of lutein diester and astaxanthin diester in MeOH solution were shown to be $1.9\times10^{10}M^{-1}Sec^{-1}$, $2.3\times10^{10}M^{-1}Sec^{-1}$ respectively. Under the experimental conditions, and within the carotenoid tested results, the larger the resonance energy is, the larger becomes the rate constant and consequently the lower the transition energy is, the better becomes the quencher.

• 대한화학회지
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• 제24권2호
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• pp.146-149
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• 1980

빌리루빈의 경우와 같이 옥소디피로메텐도 자체증감작용으로 생긴 단일상태 산소와 반응하여 광분해 하였다. 단일상태 산소의 수명이 각각 다른 용매에서 시험한 결과, 수명이 더 긴 용매에서 옥소디피로메텐의 공산화반응이 빨랐으며, 단일상태 산소의 켄칭제가 존재하는데서는 광반응이 느렸다. 더우기, 증감제를 사용하지 않은 반응에서 생성물이 증감제를 사용한 반응에서 생성물과 같았다.

• Journal of Ginseng Research
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• 제18권3호
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• pp.175-181
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• 1994

We studied the folilar wiping effects of antioxidants (ascorbate, glutathione and sodium azide), which effectively inhibited the chlorophyll bleaching or completely recorved the early stage of photosynthesis of Panax ginseng C.A. Meyer, on photosynthesis, stomatal resistance, free sugar, starch, and total saponin contents of ginseng under the excess light intensity (45 kLux) during 6 days. Ascorbate and glutathione, endogenous antioxidant, recovered photosynehtsis and stomatal resistance, and reduced the photoinhibition by the excess light intensity (45 kLux) on free sugar, starch and total saponin contents. But sodium azide, exogenous $^{1}O_2$ quencher, showed negative effect. Therefore, we assumed that carbohydrates and saponin metabolisms of ginseng by antioxidants (ascorbate, glutathione) were normal. For the reduction of inhibition by excess light in ginseng a program for the higher activation of antioxidants and antioxidative enzymes in ginseng leaf will be desirable. Key words Antioxidants, ascorbate, glutathione, Photoinhibition, ginseng.

• Bulletin of the Korean Chemical Society
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• 제20권7호
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• pp.796-800
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• 1999

Three anthrylazacrown ethers in which the anthracene fluorophore π system is separated from the electron donor atoms by one methylene group were synthesized, and their photophysical study was accomplished. These fluorescent compounds showed a maximum fluorescence intensity at pH=5 in aqueous solutions and a decrease in fluorescence intensity upon binding of paramagnetic metal cations (Mn 2+ (d 5 ), Co 2+ (d 7 ), Cu 2+ (d 9 )). The decrease in fluorescence intensity may be attributed to the paramagnetic effect of metal cations to deactivate the excited state by the nonradiative quenching process. The benzylic nitrogen was found to play an important role in changing fluorescence intensity. From the observed linear Stern-Volmer plot and the fluorescence lifetime independence of the presence of metal ions, it was inferred that the chelation enhanced fluorescence quenching (CHEQ) mechanism in the system is a ground state static quenching process. Enhanced fluorescence was also observed when an excess Na + ion was added to the quenched aqueous solution, and it was attributed to cation displacement of a complexed fluorescence quencher.