title: C8-heteroaryl-2'-deoxyguanosine adducts as conformational fluorescent probes in the NarI recognition sequence.
abstract: The optical, redox, and electronic properties of C(8)-heteroaryl-2'-deoxyguanosine (dG) adducts with C(8)-substituents consisting of furyl ((Fur)dG), pyrrolyl ((Pyr)dG), thienyl ((Th)dG), benzofuryl ((Bfur)dG), indolyl ((Ind)dG), and benzothienyl ((Bth)dG) are described. These adducts behave as fluorescent nucleobase probes with emission maxima from 379 to 419 nm and fluorescence quantum yields (Φ(fl)) in the 0.1-0.8 range in water at neutral pH. The probes exhibit quenched fluorescence with increased solvent viscosity and decreased solvent polarity. The (Fur)dG, (Bfur)dG, (Ind)dG, and (Bth)dG derivatives were incorporated into the G(3) position of the 12-mer oligonucleotide 5'-CTCG(1)G(2)CG(3)CCATC-3' that contains the recognition sequence of the NarI Type II restriction endonuclease. This sequence is widely used to study the biological activity (mutagenicity) of C(8)-arylamine-dG adducts with adduct conformation (anti vs syn) playing a critical role in the biological outcome. The modified NarI(X = (Fur)G, (Ind)G, (Bfur)G, or (Bth)G) oligonucleotides were hybridized to the complementary strand containing either C (NarI'(C)) or G (NarI'(G)) opposite the probe. The duplex structures were characterized by UV melting temperature analysis, fluorescence spectroscopy, collisional fluorescence quenching studies, and circular dichroism (CD). The emission of the probes showed sensitivity to the opposing base in the duplex, and suggested the utility of fluorescence spectroscopy to monitor probe conformation.
authors.affiliation: Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
authors.forename: Katherine M
authors.initials: KM
authors.lastname: Rankin
authors.forename: Michael
authors.initials: M
authors.lastname: Sproviero
authors.forename: Keegan
authors.initials: K
authors.lastname: Rankin
authors.forename: Purshotam
authors.initials: P
authors.lastname: Sharma
authors.forename: Stacey D
authors.initials: SD
authors.lastname: Wetmore
authors.forename: Richard A
authors.initials: RA
authors.lastname: Manderville
mesh_terms: D002942:Circular Dichroism; D018736:DNA Adducts / Q000737:chemistry*; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000737:chemistry; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000737:chemistry*; D010084:Oxidation-Reduction
chemical_list: D018736:DNA Adducts; D005456:Fluorescent Dyes; D009841:Oligonucleotides; D003849:Deoxyguanosine