The 220 MHz Nuclear Magnetic Resonance Study of a Solvent-induced Conformational Change in Flavin Adenine Dinucleotide

Kotowycz, George; Teng, Nelson N.H.; Klein, Melvin P.; Calvin, Melvin

doi:10.1016/s0021-9258(18)63610-5

Cited by 41 publications

(26 citation statements)

References 18 publications

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“…Given that FAD is likely in the stacked configuration at cryogenic temperature, it would not be surprising to see a relatively larger Stark signal if the adenine acts to decrease the “local” polarity of the solvent in the vicinity of the isoalloxazine chromophore. From NMR and CD experiments it is thought that the adenine ring is stacked on top of the xylene ring of the isoalloxazine moiety. − The lack of any large change in the Stark spectrum of FAD relative to FMN may be a clue that electronic redistribution due to the optical transitions is localized over the pyrazine−pyrimidine nuclei of the isoalloxazine. Circumstantial evidence for this conjecture comes from the absorption spectra of lumazines, which are just these nuclei without the xylene ring.…”

Section: Discussionmentioning

confidence: 99%

“…From NMR and CD experiments it is thought that the adenine ring is stacked on top of the xylene ring of the isoalloxazine moiety. [29][30][31][32] The lack of any large change in the Stark spectrum of FAD relative to FMN may be a clue that electronic redistribution due to the optical transitions is localized over the pyrazine-pyrimidine nuclei of the isoalloxazine. Circumstantial evidence for this conjecture comes from the absorption spectra of lumazines, which are just these nuclei without the xylene ring.…”

Section: Discussionmentioning

confidence: 99%

“…The electronic structures of flavins have been studied extensively by many methods, including both absorption , and luminescence spectroscopy, − time-resolved fluorescence, − resonance Raman spectroscopy, , CARS, , CD spectroscopy, − photo-CIDNP, NMR, − and linear dichroism. , It is, however, very difficult to obtain quantitative information regarding the electronic distribution of the excited states directly. In addition, there have been only a few theoretical studies of these photoreactive states …”

Section: Introductionmentioning

confidence: 99%

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Electronic Structure Measurements of Oxidized Flavins and Flavin Complexes Using Stark-Effect Spectroscopy

Stanley

Jang

1999

J. Phys. Chem. A

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Stark-effect spectroscopy (electroabsorption) measurements were obtained for oxidized flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) in frozen glycerol/H2O glasses and N(3)-methyl-N(10)-isobutyl-7,8-dimethyl-isoalloxazine in frozen n-butanol glasses at fields of up to 5 × 105 V/cm. In all three flavins, the effect of the applied electric field on the low-energy transition (S0 → S1, 450 nm band) is significantly smaller than on the higher energy transition (S0 → S2, 370 nm band). The Stark spectra indicate that the magnitude of the permanent dipole moment in the S1 state, |μ1| is only modestly different from the S0 state, |μ0|, and that there is little change in the mean polarizability for the S0 → S1 transition. The electric field effect on the S0 → S2 transition, however, shows that the magnitude of the dipole moment of the S2 state is ∼60% larger than that of the S1 state and that the change in the mean polarizability is much larger. Concentration studies indicate that the FAD dimer or larger FAD aggregates give a nonlinear enhancement of the electric field effect. The source of this enhancement is unknown but may have to do with the stacked isoalloxazine−adenine configuration extended over a dimer or larger cluster of FAD molecules.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electronic Structure Measurements of Oxidized Flavins and Flavin Complexes Using Stark-Effect Spectroscopy

Stanley

Jang

1999

J. Phys. Chem. A

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“…67,68 It has been reported that the fluorescence intensity of excited FAD in solution is about 10-fold weaker than that of excited riboflavin or FMN, [69][70][71] owing to intramolecular ET quenching with a stacked conformation between the isoalloxazine ring and the adenine moiety. Numerous experimental and theoretical studies [69][70][71][72][73][74][75][76][77][78] suggested that two FAD conformations, open and stacked, exist in solution (Fig. 3A), while this cofactor takes a folding configuration in both photolyase and cryptochrome.…”

Section: Absorption and Emission Spectra Of Flavins In Various Redox ...mentioning

confidence: 99%

Dynamics and mechanisms of DNA repair by photolyase

Liu

Wang

Zhong

2015

Phys. Chem. Chem. Phys.

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Photolyase, a class of flavoproteins, uses blue light to repair two types of ultraviolet-induced DNA damage, cyclobutane pyrimidine dimer (CPD) and pyrimidine-pyrimidone (6–4) photoproduct (6–4PP). In this perspective, we review the recent progress on the repair dynamics and mechanisms of both types of DNA restoration by photolyases. We first report the spectroscopic characterization of flavin in various redox states and the active-site solvation dynamics in photolyases. We then systematically summarize the detailed repair dynamics of damaged DNA by photolyases and a biomimetic system through resolving all elementary steps on the ultrafast timescales, including multiple intermolecular electron- and proton-transfer reactions and bond-breaking and -making processes. We determined the unique electron tunneling pathways, identified the key functional residues and revealed the molecular origin of high repair efficiency, and thus elucidate the molecular mechanisms and repair photocycles at the most fundamental level. We finally conclude that the active sites of photolyases, unlike aqueous solution for the biomimetic system, provide a unique electrostatic environment and local flexibility and thus a dedicated synergy for all elementary dynamics to maximize the repair efficiency. This repair photomachine is the first enzyme that the entire functional evolution is completely mapped out in real time.

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“…The solid lines are theoretical curves for a one one-proton ionization of pAa = 7.0. Kotowycz et al, 1969) have shown the properties of the side chain C(l') methylene protons to be sensitive indicators of intermolecular stacking interactions of the flavin in aqueous solution. Indeed, the formation of flavin dimers in both the oxidized and reduced forms in aqueous solutions has been known since the work of Gibson et al (1962).…”

Section: Resultsmentioning

confidence: 99%

Proton nuclear magnetic resonance studies of 8.alpha.-N-imidazolylriboflavin in its oxidized and reduced forms

Williamson¹,

Edmondson²

1985

Biochemistry

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The oxidized and hydroquinone forms of synthetic 8 alpha-N-imidazolylriboflavin have been investigated by proton nuclear magnetic resonance spectroscopy at 360 MHz. Proton resonances due to the imidazole ring, isoalloxazine ring, and ribityl side chain have been assigned on the basis of two-dimensional 1H-1H correlated spectra (COSY), selective decoupling, and nuclear Overhauser effect difference spectra and by comparison of computer-simulated with experimental spectra. The effect of pH on the imidazolyl resonances shows a pKa for the unsubstituted imidazole nitrogen of 6.0 +/- 0.1 for the oxidized form and a value of 7.0 +/- 0.1 for the reduced form, in good agreement with the values obtained from oxidation-reduction potential data in a previous paper [Williamson, G., & Edmondson, D. E. (1985) Biochemistry 24, 7790-7797]. Slow exchange of the flavin 8 alpha-methylene and imidazolyl C(2) protons was observed at pH 6.1 but not at pH values below 4.0 for the oxidized form of the flavin. The reduced form, but not the oxidized form, of the flavin exhibits geminal coupling of the 8 alpha-methylene protons and of the C(1') methylene protons of the ribityl side chain. The magnetic nonequivalence of the protons of these two methylene groups is suggested to result from intermolecular association of the reduced flavin in aqueous solutions at the concentrations required for the spectral experiments.

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The 220 MHz Nuclear Magnetic Resonance Study of a Solvent-induced Conformational Change in Flavin Adenine Dinucleotide

Cited by 41 publications

References 18 publications

Electronic Structure Measurements of Oxidized Flavins and Flavin Complexes Using Stark-Effect Spectroscopy

Electronic Structure Measurements of Oxidized Flavins and Flavin Complexes Using Stark-Effect Spectroscopy

Dynamics and mechanisms of DNA repair by photolyase

Proton nuclear magnetic resonance studies of 8.alpha.-N-imidazolylriboflavin in its oxidized and reduced forms

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