title: Long-wavelength fluorescence from 2-aminopurine-nucleobase dimers in DNA.
abstract: When 2-aminopurine (2AP) is substituted for adenine in DNA, it is widely accepted that its fluorescence spectrum is essentially unchanged from that of the free fluorophore. We show that 2AP in DNA exhibits long-wavelength emission and excitation bands, in addition to the familiar short-wavelength spectra, as a result of formation of a ground-state heterodimer with an adjacent, pi-stacked, natural base. The observation of dual emission from 2AP in a variety of oligodeoxynucleotide duplexes and single strands demonstrates the generality of this phenomenon. The photophysical and conformational properties of the long-wavelength-emitting 2AP-nucleobase dimer are examined. Analogous long-wavelength fluorescence is seen when 2AP pi-stacks with aromatic amino acid sidechains in the active sites of methyltransferase enzymes during DNA nucleotide flipping.
authors.affiliation: School of Chemistry and Collaborative Optical Spectroscopy, Micromanipulation and Imaging Centre, The University of Edinburgh, West Mains Road, Edinburgh EH9 3JJ, UK.
authors.forename: Eleanor Y M
authors.initials: EY
authors.lastname: Bonnist
authors.forename: Anita C
authors.initials: AC
authors.lastname: Jones
mesh_terms: D015075:2-Aminopurine / Q000737:chemistry*; D001483:Base Sequence; D004247:DNA / Q000737:chemistry*; D019281:Dimerization; D005453:Fluorescence; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000737:chemistry; D012996:Solutions; D013050:Spectrometry, Fluorescence; D013696:Temperature
chemical_list: D009841:Oligonucleotides; D012996:Solutions; D015075:2-Aminopurine; D004247:DNA