2-Aminopurine optical spectra: Solvent, pentose ring, and DNA helix melting dependence

Evans, Kervin O.; Xu, Daguang; Kim, Younsik; Nordlund, Thomas M.

doi:10.1007/bf00865278

Cited by 41 publications

(66 citation statements)

References 24 publications

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“…These energy shifts have been measured for a series of solvents [10][11][12][13]. The results of these studies are in general agreement with the predicted direction of solvatochromic shifts.…”

Section: Solvatochromic Shiftssupporting

confidence: 72%

“…Several groups have measured the solvatochromic shifts in the absorption and emission spectra of 2ΑΡ [10][11][12][13]. In relatively non-polar solvents such as dioxane and ethyl acetate, the peak of the lowest-energy band in the absorption spectrum is found at approximately 4.11 eV (302 nm), and that of the fluorescence emission at 3.59 eV (355 nm).…”

Section: Introductionmentioning

confidence: 99%

“…Notably, the spectral shifts observed in water did not follow the predictions of the classical theory of dipolar interactions. This observation led Evans et al [13] to conclude that 2ΑΡ undergoes a specific intermolecular interaction in water, which could be hydrogen bonding. However, this hypothesis has not been tested by any direct measurement of hydrogen bond sites or affinities.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Spectroscopy of 2-aminopurine: An MCSCF Study

Rachofsky¹,

Ross²,

Krauß³

et al. 1998

Acta Phys. Pol. A

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2-aminopurine is a highly fluorescent isomer of adenine that can be incorporated into DNA as a probe of structure, dynamics, and protein-DNA interactions. Interpretation of the fluorescence of 2-aminopurine in DNA requires a model of the electronic structure of this fluorophore in its ground and excited states. To this end, electronic structures and energies of the ground and lowest singlet excited states of 2-amino-9-methylpurine were calculated by the multiconfiguration self-consistent field method supplemented by multiconfiguration perturbation theory. The molecular geometry was optimized in both of these electronic states to permit investigation of both electronic excitation and fluorescence emission. The predicted energies and transition dipoles were in good agreement with experiment. The permanent molecnlar dipole of 2-amino-9-methylpιιrine increased upon excitation, suggesting that both the absorption and emission spectra should shift to slightly lower energies in polar solvents. The anomalous spectral shifts observed in water suggest that 2-aminopurine undergoes hydrogen bonding that better stabilizes the ground state than the excited state. From the calculated electrostatic potentials of these two states, the position at which this hydrogen bond forms was predicted. These results form a basis for understanding the excited states and possible intermolecular interactions of 2-aminopurine in DNA.

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Section: Solvatochromic Shiftssupporting

confidence: 72%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spectroscopy of 2-aminopurine: An MCSCF Study

Rachofsky¹,

Ross²,

Krauß³

et al. 1998

Acta Phys. Pol. A

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“…The ground and lowest electronic excited states have a π-π* character [20]. In aqueous solutions the quantum efficiency is about 0.7 [3], maxima of absorption and emission are about 305 nm and 370 nm respectively [4,21] and the fluorescence intensity decays are mono-exponential with the fluorescence lifetime of about 12 ns [8,22]. pH has not been found to have any effect on absorption and emission of 2AP, indicating its single protonation state in neutral solution [3,22].…”

Section: Introductionmentioning

confidence: 99%

Fluorescence intensity decays of 2-aminopurine solutions: Lifetime distribution approach

Bharill

Sarkar

Ballin

et al. 2008

Analytical Biochemistry

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The fluorescent adenine analogue 2-aminopurine (2AP) has been used extensively to monitor conformational changes and macromolecular binding events involving nucleic acids because its fluorescence properties are highly sensitive to changes in chemical environment. Furthermore, site-specific incorporation of 2AP permits local DNA and RNA conformational events to be discriminated from the global structural changes monitored by UV/Vis spectroscopy and circular dichroism. However, while the steady-state fluorescence properties of 2AP have been well defined in diverse settings, interpretation of 2AP fluorescence lifetime parameters has been hampered by the heterogeneous nature of multi-exponential 2AP intensity decays observed across populations of microenvironments. To resolve this problem, we have tested the utility of multi-exponential versus continuous Lorentzian lifetime distribution models to describe fluorescence intensity decays from 2AP in diverse chemical backgrounds and within the context of RNA. Heterogeneity was introduced into 2AP intensity decays by mixing solvents of differing polarities, or by adding quenchers under high viscosity to evaluate the transient effect. Heterogeneity of 2AP fluorescence within the context of a synthetic RNA hairpin was introduced by structural remodeling using a magnesium salt. In each case, except folded RNA which required a bimodal distribution, 2AP lifetime properties were well described by single Lorentzian distribution functions, abrogating the need to introduce additional discrete lifetime subpopulations. Rather, heterogeneity in fluorescence decay processes was accommodated by the breadth of each distribution. This approach also permitted solvent relaxation effects on 2AP emission to be assessed by comparing lifetime distributions at multiple wavelengths. Together, these studies provide a new perspective for the interpretation of 2AP fluorescence lifetime properties, which will further the utility of this Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. HHS Public Access Author Manuscript Author ManuscriptAuthor ManuscriptAuthor Manuscript fluorophore in analyses of the complex and heterogeneous structural microenvironments associated with nucleic acids.

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“…AP is an environment-sensitive fluorophore. Calculations show that changes in the dipole moment between the ground and the excited states could be up to 3-5 D, which results in a 10-12 nm shift in the position of fluorescence maximum in environments with different polarities (30). A red shift of 6 and 4 nm was observed in emission maximum of duplexes I/II and V/VI/VIII, respectively, upon adduct formation.…”

Section: Discussionmentioning

confidence: 97%

Fluorescence Probing of Aminofluorene-Induced Conformational Heterogeneity in DNA Duplexes

Jain

Reshetnyak²,

Gao³

et al. 2008

Chem. Res. Toxicol.

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Fluorescence spectroscopy was used to study carcinogen-induced conformational heterogeneity in DNA duplexes. The fluorophore 2-aminopurine (AP) was incorporated adjacent (5′) to the lesion (G*) in eight different DNA duplexes [d(5′-CTTCTPG*NCCTC-3′):d(5′-GAGGNXTAGAAG-3′), G* = FAF adduct, P = AP, N = G, A, C, T, and X = C, A] modified by FAF [N-(2′-deoxyguanosin-8-yl)-7-fluoro-2-aminofluorene], a fluorine-tagged model DNA adduct derived from the potent carcinogen 2-aminofluorene. Steady-state measurements showed that fluorescence intensity and Stern-Volmer constants (K sv ) derived from acrylamide quenching experiments decreased for all carcinogen-modified duplexes relative to the controls, which suggests greater AP stacking in the duplex upon adduct formation. Conformation-specific stacking of AP with the neighboring adduct was evidenced by a sequence-dependent variation in fluorescence intensity, position of emission maximum, degree of emission quenching by acrylamide, and temperature-dependent spectral changes. The magnitude of stacking was in the order of FAF residue in base-displaced stacked (S) > minor groove wedged (W) > major groove B type (B). This work represents a novel utility of AP in probing adduct-induced conformational heterogeneities in DNA duplexes.

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2-Aminopurine optical spectra: Solvent, pentose ring, and DNA helix melting dependence

Cited by 41 publications

References 24 publications

Spectroscopy of 2-aminopurine: An MCSCF Study

Spectroscopy of 2-aminopurine: An MCSCF Study

Fluorescence intensity decays of 2-aminopurine solutions: Lifetime distribution approach

Fluorescence Probing of Aminofluorene-Induced Conformational Heterogeneity in DNA Duplexes

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