The mechanism of riboflavin fluorescence quenching by nucleophiles

Иванов, В. Л.; Uzhinov, B. M.; Lyashkevich, S. Yu.

doi:10.3103/s0027131410040048

Cited by 4 publications

(6 citation statements)

References 15 publications

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“…Direct H-abstraction from 32 by reactive oxygen species as an alternative or additional route to amidyl radical 34 cannot be excluded at this stage of the investigation. In 2010, Ivanov et al reported a photoinduced electron transfer from the nitrite anion to excited riboflavin, confirmed by fluorescence quenching experiments . We find emission quenching for the acetylated derivative of the dye by sodium nitrite.…”

Section: Resultssupporting

confidence: 78%

“…In 2010, Ivanov et al reported a photoinduced electron transfer from the nitrite anion to excited riboflavin, confirmed by fluorescence quenching experiments. 40 We find emission quenching for the acetylated derivative of the dye by sodium nitrite. However, in contrast to Ivanov's observation, we observe dynamic quenching (Stern−Volmer constant K SV = 14.1 mol −1 ) of the emission of RFTA upon addition of NaNO 2 in an acetonitrile−water solvent mixture (Figure 1).…”

Section: ■ Results and Discussionmentioning

confidence: 79%

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Visible-Light-Mediated Nitration of Protected Anilines

Düsel

König

2018

J. Org. Chem.

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The photocatalytic nitration of protected anilines proceeds with riboflavin tetraacetate as an organic photoredox catalyst. Sodium nitrite serves as the NO source in this visible-light-driven room temperature reaction. Various nitroanilines are obtained in moderate to good yields without the addition of acid or stoichiometric oxidation agents. The catalytic cycle is closed by aerial oxygen as the terminal oxidant.

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Section: Resultssupporting

confidence: 78%

Section: ■ Results and Discussionmentioning

confidence: 79%

Visible-Light-Mediated Nitration of Protected Anilines

Düsel

König

2018

J. Org. Chem.

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“…However, the formation of an intramolecular ground-state complex between the isoalloxazine ring and the adenine moiety leads FAD to a weak fluorescent compared with its natural resource riboflavin in an aqueous solution. The fluorescence is further quenched by Trp and Tyr at their ground state once FAD is incorporated with apoenzyme because excited Trp and Tyr are quenchable by the weak electron-accepting amides possessing particularly high highest occupied molecular orbits. , …”

Section: Resultsmentioning

confidence: 99%

“…The fluorescence is further quenched by Trp and Tyr at their ground state once FAD is incorporated with apoenzyme because excited Trp and Tyr are quenchable by the weak electron-accepting amides possessing particularly high highest occupied molecular orbits. 47,48 As mentioned above, the fluorescence intensity (λ = 520 nm) is distinctly different between the oxidative and the reductive states of DAA-flavin. Thereby, it is suggested that the interaction between the introduced DAA-flavin and the cofactor FAD would result in a fluorescence change in GOx@ Fla-c-PAAm during the enzymatic process.…”

Section: Acs Applied Materials and Interfacesmentioning

confidence: 86%

Fabrication of Activity-Reporting Glucose Oxidase Nanocapsules with Oxygen-Independent Fluorescence Variation

Chen

Huang

Jiang

et al. 2018

ACS Appl. Mater. Interfaces

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Glucose oxidase (GOx) has seen large-scale technological applications, and the determinations of its activity that is directly related to the enzymatic functions are extremely important. However, conventional methods to analyze the enzymatic activity involving high oxygen dependency and indirect redox reactions are usually tedious and restricted in complicated environments. For analyzing enzymatic activity by direct detection of the electron signals from the active centers, mediators are often used for facilitating the electron transfer. Differing from common methods of preparing electron mediators-contained GOx composites, a strategy aiming at remolding of the enzyme itself has been proposed in this work. Cofactor-like molecule 2'-diallyamino-ethyl flavin (DAA-flavin) derived from riboflavin is synthesized and incorporated as cross-linker into the polyacrylamide (PAAm) network around GOx surface by in situ polymerization to obtain enzyme nanocapsules termed as GOx@Fla-c-PAAm. The peripheral polymer shell confines the orientation of GOx and prevents it from denaturing, whereas incorporated DAA-flavin can replace the oxygen as an alternative electron acceptor to interact with the active centers of GOx in the presence of the substrate, thus giving the nanocapsules oxygen-independent characteristics. The introduced unlimited cofactor-like molecules endow the nanocapsules redox-related fluorescence, and the intensity variation is closely correlated with the enzymatic activity. There is a high goodness of fitting ( R ∼ 0.990) between the slope of linear fluorescence-time plots and enzymatic activity, thereby making the nanocapsules a reliable activity-reporting enzymatic nanosystem with oxygen-independent fluorescence variation for further extended potential application in biofuel cells and biosensors.

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“…quenching of fluorescence) instead of the destruction of the riboflavin vitamers, as observed when the thiamine vitamers were exposed to metabisulphite. The quenching of riboflavin by sulphites and other nucleophiles has been described before (57,58), with relative differences in the magnitude of the various riboflavin vitamers (57).…”

Section: Resultsmentioning

confidence: 98%

Vitamins in brewing: effects of post-fermentation treatments and exposure and maturation on the thiamine and riboflavin vitamer content of beer

et al. 2016

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Post‐fermentation processes and maturation are important steps in beer production as they help to shape the organoleptic properties and stabilize the final product. Brewers can use a variety of processing aids (e.g. isinglass, PVPP, etc.) and processes (e.g. pasteurization, bottle conditioning, etc.) to achieve a desired final product with a desirable shelf life; however, these processes can have detrimental effects on the vitamin content of the beer. This research found that heat treatments have a marked influence on the decrease in the thiamine diphosphate vitamer, while PVPP and silica treatments have a greater influence on the decrease in riboflavin vitamers. Refrigeration, filtration or centrifugation have no, or only very limited, influence on thiamine or riboflavin vitamers, while application of isinglass, bentonite, tannic acid and SO2 causes a decrease in both thiamine and riboflavin vitamers. Storage of beer at refrigerated temperatures appears to provide protection against significant degradation of both thiamine and riboflavin vitamers; however, storage of filtered beer at elevated temperatures shows a decrease in thiamine diphosphate and riboflavin. Storage of bottle‐conditioned beer at elevated temperatures shows a marked decrease in yeast viability, accompanied by a decrease in thiamine diphosphate and free riboflavin, and a marked increase in free thiamine. These findings provide an insight into the reason why there is a significant variation in the vitamer content of beers, even within a single beer style. Copyright © 2016 The Institute of Brewing & Distilling

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The mechanism of riboflavin fluorescence quenching by nucleophiles

Cited by 4 publications

References 15 publications

Visible-Light-Mediated Nitration of Protected Anilines

Visible-Light-Mediated Nitration of Protected Anilines

Fabrication of Activity-Reporting Glucose Oxidase Nanocapsules with Oxygen-Independent Fluorescence Variation

Vitamins in brewing: effects of post-fermentation treatments and exposure and maturation on the thiamine and riboflavin vitamer content of beer

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