title: Fluorescence Turn-On Sensing of DNA Duplex Formation by a Tricyclic Cytidine Analogue.
abstract: Most fluorescent nucleoside analogues are quenched when base stacked and some maintain their brightness, but there has been little progress toward developing nucleoside analogues that markedly increase their fluorescence upon duplex formation. Here, we report on the design and synthesis of a new tricyclic cytidine analogue, 8-diethylamino-tC (8-DEA-tC), that responds to DNA duplex formation with up to a 20-fold increase in fluorescent quantum yield as compared with the free nucleoside, depending on neighboring bases. This turn-on response to duplex formation is the greatest of any reported nucleoside analogue that can participate in Watson-Crick base pairing. Measurements of the quantum yield of 8-DEA-tC mispaired with adenosine and, separately, opposite an abasic site show that there is almost no fluorescence increase without the formation of correct Watson-Crick hydrogen bonds. Kinetic isotope effects from the use of deuterated buffer show that the duplex protects 8-DEA-tC against quenching by excited state proton transfer. These results, supported by DFT calculations, suggest a rationale for the observed photophysical properties that is dependent on duplex integrity and the electronic structure of the analogue.
authors.affiliation: Department of Chemistry and Biochemistry, San Diego State University , San Diego, California 92182, United States.
authors.forename: Dillon D
authors.initials: DD
authors.lastname: Burns
authors.affiliation: Department of Chemistry and Biochemistry, San Diego State University , San Diego, California 92182, United States.
authors.forename: Kristine L
authors.initials: KL
authors.lastname: Teppang
authors.affiliation: Department of Chemistry and Biochemistry, San Diego State University , San Diego, California 92182, United States.
authors.forename: Raymond W
authors.initials: RW
authors.lastname: Lee
authors.affiliation: Department of Chemistry and Biochemistry, San Diego State University , San Diego, California 92182, United States.
authors.forename: Melissa E
authors.initials: ME
authors.lastname: Lokensgard
authors.affiliation: Department of Chemistry and Biochemistry, San Diego State University , San Diego, California 92182, United States.
authors.forename: Byron W
authors.identifier: 0000-0002-0052-6067
authors.initials: BW
authors.lastname: Purse
mesh_terms: D003562:Cytidine / Q000031:analogs & derivatives* / Q000737:chemistry; D004247:DNA / Q000737:chemistry*; D005453:Fluorescence; D006860:Hydrogen Bonding; D007700:Kinetics; D009690:Nucleic Acid Conformation; D011789:Quantum Theory
chemical_list: C000627252:8-diethylamino tricyclic cytidine; D003562:Cytidine; D004247:DNA