Journal ArticleDOI
Protein-flavonol interaction: fluorescence spectroscopic study.
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TLDR
Analysis of relevant spectroscopic data leads to the conclusions that two binding sites are involved in BSA–3HF interaction, and the interaction is slightly positively cooperative in nature with a similar binding constant.Abstract:
Recent studies have shown that various synthetic as well as therapeutically active naturally occurring flavonols possess novel luminescence properties that can potentially serve as highly sensitive monitors of their microenvironments in biologically relevant systems. We report a study on the interactions of bovine serum albumin (BSA) with the model flavonol 3-hydroxyflavone (3HF), using the excited-state proton-transfer (ESPT) luminescence of 3HF as a probe. Upon addition of BSA to the flavonoid solutions, we observe remarkable changes in the absorption, ESPT fluorescence emission and excitation profiles as well as anisotropy (r) values. Complexation of 3HF with protein results in a pronounced shift (20 nm) of the ESPT emission maximum of the probe (from lambda(max)(em) = 513 nm to lambda(max)(em) = 533 nm) accompanied by a significant increase in fluorescence intensity. The spectral data also suggest that, in addition to ESPT, the protein environment induces proton abstraction from 3HF leading to formation of anionic species in the ground state. Fairly high values of anisotropy are observed in the presence of BSA for the tautomer (r = 0.25) as well as anion (r = 0.35) species of 3HF, implying that both the species are located in motion-restricted environments of BSA molecules. Analysis of relevant spectroscopic data leads to the conclusions that two binding sites are involved in BSA-3HF interaction, and the interaction is slightly positively cooperative in nature with a similar binding constant of 1.1 - 1.3 x 10(5) M(-1) for both these sites. Proteins 2001;43:75-81.read more
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Green Tea Catechins and Cardiovascular Health : An Update
TL;DR: Takeaway is that catechins may be novel plant-derived small molecules for the prevention and treatment of cardiovascular diseases and the underlying mechanisms for these actions are discussed.
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Studies of interaction between colchicine and bovine serum albumin by fluorescence quenching method
TL;DR: In this article, the interaction between colchicine and bovine serum albumin (BSA) was investigated by fluorescence and UV-Vis absorption spectroscopy, and the modified Stern-Volmer quenching constant K a and corresponding thermodynamic parameters Δ H, Δ G, Δ S at different temperatures were calculated.
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Interaction of β-Lactoglobulin with Resveratrol and its Biological Implications
TL;DR: In this article, the interaction of resveratrol with beta-lactoglobulin was investigated using circular dichroism, fluorescence and UV-vis absorbance, and the binding constant for the 2-way interaction was found to be between 10(4 and 10(6) M (-1), as determined by protein or polyphenol fluorescence.
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The red‐edge effects: 30 years of exploration
TL;DR: Red-edge effects were discovered for electron-transfer and proton-transfer reactions if they depended on the dynamics of the environment and stimulated the emergence and development of cryogenic energy-selective and single-molecular techniques that became valuable tools in their own right in chemistry and biophysics research.
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Green tea as inhibitor of the intestinal absorption of lipids : potential mechanism for its lipid-lowering effect
Sung I. Koo,Sang K. Noh +1 more
TL;DR: The available information strongly suggests that green tea or its catechins may be used as safe and effective lipid-lowering therapeutic agents.
References
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Journal ArticleDOI
Excited-state intramolecular proton transfer as a fluorescence probe for protein binding-site static polarity
Alexander Sytnik,Michael Kasha +1 more
TL;DR: It is shown that PT fluorescence of HAP can serve as a protein-binding-site static-polarity calibrator, shifting from a lambda max of 612 nm in cyclohexane to 585 nm in ethanol at 298 K, contrary to the usual dispersion red shift.
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Interplay between excited-state intramolecular proton transfer and charge transfer in flavonols and their use as protein-binding-site fluorescence probes
TL;DR: The utility of DHF as a discriminating fluorescence probe for protein binding sites is suggested by the strong dependence of the charge-transfer fluorescence on polarity of the environment and by various static and dynamic parameters of the Charge-transfer and proton- transfer fluorescence which can be determined.
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Energy transfer to a proton-transfer fluorescence probe: Tryptophan to a flavonol in human serum albumin
Alexander Sytnik,Igor Litvinyuk +1 more
TL;DR: A protein fluorescence probe system, coupling excited-state intermolecular Förster energy transfer and intramolecular proton transfer (PT), is presented and it is demonstrated that two binding sites are involved in the human serum albumin-3-HF interaction.
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Flavones are inhibitors of HIV-1 proteinase.
TL;DR: Substituted gamma-chromones were found to weakly inhibit HIV-1 proteinase, an important enzyme in the replication and processing of the AIDS virus, and a possible mechanism for flavone-induced inhibition is proposed.
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Inhibition of phosphorylase kinase, and tyrosine protein kinase activities by quercetin.
TL;DR: The data suggest that quercetin has differential effect on different protein kinase activities and it may be used as a tool to probe the role of various protein kinases in cell function.