Photophysics and Biological Applications of 7-Azaindole and Its Analogs

Smirnov, Alexandre V.; English, Douglas S.; Rich, Rebecca L.; Lane, James W.; Teyton, Luc; Schwabacher, Alan W.; Luo, Siquan; Thornburg, Robert W.; Petrich, Jacob W.

doi:10.1021/jp9630232

Cited by 156 publications

(165 citation statements)

References 84 publications

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“…The glyco-linkage causes the fluorescence intensity of 7a In to increase by about 23 times. This was expected because similar increase was observed if 7a In was N − 1 methylated [31][32][33][34][35][36][37][38]. However, incorporation of 7a In into DNA quenches its fluorescence significantly as the fluorescence intensity of 7a In-ss and 7a In-ds are significantly lower than that for 7a In-r.…”

Section: Incorporation Of 7a In Into Dna Oligonucleotidesupporting

confidence: 65%

“…One interesting fluorescent molecule used for studying protein structure and dynamics is 7-azaindole ( 7a In) [31][32][33][34][35][36][37][38]. 7a In is weakly fluorescent in water due to dimer formation [34][35][36].…”

Section: Introductionmentioning

confidence: 99%

“…The fluorescence property of 7a In, as well as its 3-alanyl derivative, 7-azatryptophan, is well understood. It has been incorporated into peptides to obtain peptide/protein structural information [31,33,39]. Due to the unique fluorescence properties of this molecule, we wish to report the incorporation of 7a In into duplex DNA to examine its fluorescence properties in 2′-deoxyriboside, in single and double strand DNA, and the fluorescence change during DNA duplex thermomelting.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and fluorescence study of 7-azaindole in DNA oligonucleotides replacing a purine base

Wang¹,

Stringfellow²,

Dong³

et al. 2002

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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The fluorescence spectroscopy of 7-azaindole ( 7a In) incorporated in DNA oligonucleotides is investigated. Incorporation of 7a In into DNA oligonucleotides is accomplished through standard solid-phase phosphoramidite chemistry. Fluorescence emission of the 7a In chromophore shifts slightly to the red (from 386 nm to 388 nm) upon glycosylation at the N − 1 position, but its relative fluorescence quantum yield increases 23 times, from 0.023 to 0.53. Upon incorporation into DNA, the fluorescence emission of 7a In is greatly quenched with fluorescence quantum yields of 0.020 and 0.016 in single and double strand DNA, respectively. The fluorescence emission for 7a In in DNA oligonucleotides shifts to the blue with an emission maximum at 379 nm. Both the strong fluorescence quenching and the blue shift of the emission spectrum signify that 7a In is stacked with neighboring DNA bases in both single and double strand DNA. As the duplex DNA melts due to temperature increase, the fluorescence of the 7a In chromophore increases, indicating the transition from the less fluorescent duplex DNA to the more fluorescent single strand DNA. Since this fluorescent 7a In is a structural analog of purine, its fluorescence property may be utilized as a probe for studying nucleic acid structure and dynamics.

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Section: Incorporation Of 7a In Into Dna Oligonucleotidesupporting

confidence: 65%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Synthesis and fluorescence study of 7-azaindole in DNA oligonucleotides replacing a purine base

Wang¹,

Stringfellow²,

Dong³

et al. 2002

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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“…58,59,[62][63][64]69 Phototautomerization has also been discovered in complexes of 7AI with alcohols and water. [70][71][72][73][74][75][76][77][78][79][80][81][82][83][84] We have been carrying out detailed studies of bifunctional chromophores based on indole, pyrrole, pyridine, and carbazole units, such as 2-(2′-pyridyl)indoles, 4,5,8,13,18,20,21,31 2-(2′-pyridyl)-pyrrole, 32,85 7-(pyridyl)indoles, 35 dipyrido[2,3-a:3′,2′-i]carbazole, 10,22,25 7,8,9,10-tetrahydro-11H-pyrido [2,3-a]carbazole, 18,22 or 1H-pyrrolo [3,2-h]quinoline. 19,21,22,27,31,86 These molecules, structurally similar to 7AI, differ in the number of bonds between the proton donor (the NH group) and the acceptor (pyridine...…”

Section: Introductionmentioning

confidence: 99%

Structure and Photophysics of 2-(2‘-Pyridyl)benzindoles: The Role of Intermolecular Hydrogen Bonds

et al. 2007

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The photophysical properties of two isomeric 2-(2′-pyridyl)benzindoles depend on the environment. Strong fluorescence is detected in nonpolar and polar aprotic solvents. In the presence of alcohols, the emission reveals an unusual behavior. Upon titration of n-hexane solutions with ethanol, the fluorescence intensity goes through a minimum and then increases with rising alcohol concentration. Transient absorption and timeresolved emission studies combined with ground-and excited-state geometry optimizations lead to the conclusion that two rotameric forms, syn and anti, coexist in alcohols, whereas in nonpolar and aprotic polar media, only the syn conformation is present. The latter can form cyclic complexes with alcohols, which are rapidly depopulated in the excited state. In the presence of excess alcohol, syn f anti rotamerization occurs in the ground state, promoted by the cooperative action of nonspecific and specific effects such as solvent polarity increase and the formation of hydrogen bonds to both donor and acceptor sites of the bifunctional compounds.

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“…Many past studies have focused on Trp-based unnatural amino acids, including azatryptophans (5,6,12) and various indole-ring substituted analogs (13)(14)(15)(16), aiming to identify useful biological fluorophores. Whereas some Trp analogs indeed exhibit improved fluorescent properties over Trp, none of them has found broad applications due to certain photophysical limitations.…”

mentioning

confidence: 99%

Blue fluorescent amino acid for biological spectroscopy and microscopy

Hilaire

Ahmed

Lin

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

111

119

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Many fluorescent proteins are currently available for biological spectroscopy and imaging measurements, allowing a wide range of biochemical and biophysical processes and interactions to be studied at various length scales. However, in applications where a small fluorescence reporter is required or desirable, the choice of fluorophores is rather limited. As such, continued effort has been devoted to the development of amino acid-based fluorophores that do not require a specific environment and additional time to mature and have a large fluorescence quantum yield, long fluorescence lifetime, good photostability, and an emission spectrum in the visible region. Herein, we show that a tryptophan analog, 4-cyanotryptophan, which differs from tryptophan by only two atoms, is the smallest fluorescent amino acid that meets these requirements and has great potential to enable in vitro and in vivo spectroscopic and microscopic measurements of proteins.fluorescence protein | fluorescence probe | unnatural amino acid | imaging O f the amino acids that are inherently responsible for the fluorescence of proteins, tyrosine (Tyr), tryptophan (Trp), and phenylalanine (Phe), Trp is the most widely used fluorescence reporter of protein structure, function, and dynamics, as its fluorescence quantum yield (QY) is comparatively large and is also sensitive to environment (1-3). However, Trp absorbs/emits in the UV wavelength region and has low photostability. Combined, these factors render this naturally occurring fluorescent amino acid hardly useful as a fluorophore for single-molecule measurements (4) and imaging applications, especially under in vivo conditions. For this reason, significant efforts have been devoted to identifying small unnatural fluorophores (5-11) that could overcome this limitation. So far, only naphthalene-based fluorophores, such as prodan (8, 9) and aladan (11) have been shown to be useful in this regard. However, these fluorophores are not structurally based on any naturally occurring amino acids and are larger in size than Trp, making them less attractive in applications where there are stringent requirements for the fluorophore size and structure. Therefore, the development of a smaller, ideally amino acid-based, fluorophore that does not require additional time to mature, have a large fluorescence QY, long fluorescence lifetime, good photostability, and an emission spectrum in the visible range, would enhance biological research. Herein, we show that a Trp analog, 4-cyanotryptophan (4CN-Trp), meets these requirements and has great potential to expand biological fluorescence spectroscopy and microscopy into additional territory.Many past studies have focused on Trp-based unnatural amino acids, including azatryptophans (5, 6, 12) and various indole-ring substituted analogs (13-16), aiming to identify useful biological fluorophores. Whereas some Trp analogs indeed exhibit improved fluorescent properties over Trp, none of them has found broad applications due to certain photophysical limitations. Recently, Ta...

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Photophysics and Biological Applications of 7-Azaindole and Its Analogs

Cited by 156 publications

References 84 publications

Synthesis and fluorescence study of 7-azaindole in DNA oligonucleotides replacing a purine base

Synthesis and fluorescence study of 7-azaindole in DNA oligonucleotides replacing a purine base

Structure and Photophysics of 2-(2‘-Pyridyl)benzindoles: The Role of Intermolecular Hydrogen Bonds

Blue fluorescent amino acid for biological spectroscopy and microscopy

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