title: Small-molecule binding at an abasic site of DNA: strong binding of lumiflavin for improved recognition of thymine-related single nucleotide polymorphisms.
abstract: The binding behavior of lumiflavin, a biologically vital ligand, with DNA duplexes containing an abasic (AP) site and various target nucleobases opposite the AP site is studied. Lumiflavin binds selectively to thymine (T) opposite the AP site in a DNA duplex over other nucleobases. Using 1H NMR spectroscopy and fluorescence measurements, we show that ligand-DNA complexation takes place by hydrogen-bond formation between the ligand and the target nucleobases and by stacking interactions between the ligand and the nucleobases flanking the AP site. From isothermal titration calorimetric experiments, we find that ligand incorporation into the AP sites is primarily enthalpy-driven. Examination of ionic strength dependency of ligand binding with DNA reveals that ligand-DNA complexation is a manifestation of both electrostatic and nonelectrostatic interactions and that the contribution from the nonelectrolyte effect is fundamental for the stabilization of the ligand-DNA complex. In comparison to riboflavin, reported previously as a T-selective ligand, lumiflavin binds to the DNA much more strongly and is a more promising ligand for efficient detection of T-related single nucleotide polymorphisms.
authors.affiliation: Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan.
authors.forename: N B
authors.initials: NB
authors.lastname: Sankaran
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Sato
authors.forename: Fuyuki
authors.initials: F
authors.lastname: Sato
authors.forename: Burki
authors.initials: B
authors.lastname: Rajendar
authors.forename: Kotaro
authors.initials: K
authors.lastname: Morita
authors.forename: Takehiro
authors.initials: T
authors.lastname: Seino
authors.forename: Seiichi
authors.initials: S
authors.lastname: Nishizawa
authors.forename: Norio
authors.initials: N
authors.lastname: Teramae
mesh_terms: D002151:Calorimetry; D004247:DNA / Q000737:chemistry* / Q000378:metabolism*; D005415:Flavins / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D009691:Nucleic Acid Denaturation; D009994:Osmolar Concentration; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics; D013941:Thymine / Q000737:chemistry* / Q000378:metabolism*; D017186:Titrimetry; D044366:Transition Temperature
chemical_list: D005415:Flavins; C001922:lumiflavin; D004247:DNA; D013941:Thymine