Spectral and redox properties of benzodipteridine. A pulse radiolysis, laser flash photolysis and semi-empirical molecular orbital study

Heelis, Paul F.; Parsons, Barry J.; Yano, Yumihiko

doi:10.1039/a604659b

Cited by 4 publications

(2 citation statements)

References 12 publications

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“…If the fluorescence quenching is a result of the altered relative orientation or distance of the flavin isoalloxazine ring π-system with respect to an aromatic stacking partner, then photochemical excitation of the flavin could cause a shift of the chromophore within the binding pocket. Indeed, semiempirical calculations demonstrate that photoexcitation can lead to an increase in electron density at the N5 position of the isoalloxazine ring ( , ) that can be correlated with an increase in proton affinity to N5 upon photochemical excitation ( , ). Furthermore, it is known that the presence of H-bonding interactions at N5 can act to lower the energy of the lowest unoccupied molecular orbital (LUMO) of flavins ( , ).…”

Section: Discussionmentioning

confidence: 99%

Spectroscopic and Mutational Analysis of the Blue-Light Photoreceptor AppA: A Novel Photocycle Involving Flavin Stacking with an Aromatic Amino Acid

et al. 2003

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The flavoprotein AppA is a blue-light photoreceptor that functions as an antirepressor of photosynthesis gene expression in the purple bacterium Rhodobacter sphaeroides. Heterologous expression studies show that FAD binds to a 156 amino acid N-terminal domain of AppA and that this domain is itself photoactive. A pulse of white light causes FAD absorption to be red shifted in a biphasic process with a fast phase occurring in <1 micros and a slow phase occurring at approximately 5 ms. The absorbance shift was spontaneously restored over a 30 min period, also in a biphasic process as assayed by fluorescence quenching and electronic absorption analyses. Site-directed replacement of Tyr21 with Leu or Phe abolished the photochemical reaction implicating involvement of Tyr21 in the photocycle. Nuclear magnetic resonance analysis of wild-type and mutant proteins also indicates that Tyr21 forms pi-pi stacking interactions with the isoalloxazine ring of FAD. We propose that photochemical excitation of the flavin results in strengthening of a hydrogen bond between the flavin and Tyr 21 leading to a stable local conformational change in AppA.

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Section: Discussionmentioning

confidence: 99%

Spectroscopic and Mutational Analysis of the Blue-Light Photoreceptor AppA: A Novel Photocycle Involving Flavin Stacking with an Aromatic Amino Acid

et al. 2003

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“…240 The one-electron reduced form of benzodipteridine was found to be less basic than £avin. 241 One-electron oxidized and reduced forms of Rhodamine 123, attributed to the radical cation and radical anion with absorption maxima at 450 and 390 nm, respectively, were produced by pulse radiolysis. 242 The OH Á radical-induced one-electron oxidation of the azo-dye methyl orange occurs at the nitrogen centre, whereas it results in an addition to the benzene ring in the case of the azo-dye calmagite.…”

Section: Organic Solutesmentioning

confidence: 99%

7 Radiation chemistry

Belloni

Delcourt

Houée-Levin⊥

et al. 2000

Annu. Rep. Prog. Chem., Sect. C

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We try in this review to survey advances in all the aspects of Radiation Chemistry (the effects of high energy or ionizing radiation), both basic and applied, made during the period 1995^1999, after the last report issued at the end of 1994. 1 Classically, two main classes of studies are relevant. The ¢rst one includes the primary phenomena induced by the interaction of high-energy radiation with a chemical system. The way the energy is spatially deposited is indeed highly nonhomogeneous and depends on the type of radiation considered. Mutual reactions between the primary species produced also depend on their initial spatial distribution, and therefore on the energy absorption pattern. The kinetic aspects derive directly from the initial events following radiation absorption and thus, when observed at times as short as possible, give useful information on the early energy distribution for each of the radiation types, X-and g-photons, electrons and heavy particles, and, on the in£uence of their intensity and energy per particle.The second class of studies utilizes the background knowledge of radiation chemistry to generate and then to observe the fate of chemical transient species known to be involved in very important chemical or biochemical processes. Numerous data, such as the nature of reaction products, the absolute rate constants, the sequence of elementary reactions constituting a mechanism, and the thermodynamic and spectroscopic properties of short-lived species have been attained. This kind of study of transients and reaction mechanisms, which can be approached only by pulse techniques (essentially pulse radiolysis or laser photolysis, each with its speci¢c advantages), constitutes the new ¢eld of fast to ultrafast chemistry. It concerns extended domains of physical, organic, inorganic, and bio-chemistry. Moreover, the understanding of mechanisms is quite helpful in suggesting new ways of synthesis or degradation induced by irradiation and is now extensively used in developing various speci¢c processes in applied chemistry. The number of studies on the chemical mechanisms and in applied radiation chemistry constitutes an increased fraction of the total publications in radiation chemistry, which we estimate to be around 4000 over the period considered (almost constant compared to the preceding 5-year

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ChemInform Abstract: Spectral and Redox Properties of Benzodipteridine. A Pulse Radiolysis, Laser Flash Photolysis and Semi‐Empirical Molecular Orbital Study.

1997

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Spectral and redox properties of benzodipteridine. A pulse radiolysis, laser flash photolysis and semi-empirical molecular orbital study

Cited by 4 publications

References 12 publications

Spectroscopic and Mutational Analysis of the Blue-Light Photoreceptor AppA: A Novel Photocycle Involving Flavin Stacking with an Aromatic Amino Acid

Spectroscopic and Mutational Analysis of the Blue-Light Photoreceptor AppA: A Novel Photocycle Involving Flavin Stacking with an Aromatic Amino Acid

7 Radiation chemistry

ChemInform Abstract: Spectral and Redox Properties of Benzodipteridine. A Pulse Radiolysis, Laser Flash Photolysis and Semi‐Empirical Molecular Orbital Study.

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