title: In vitro studies on the behavior of salmeterol xinafoate and its interaction with calf thymus DNA by multi-spectroscopic techniques.
abstract: The salmeterol xinafoate (SX) binding to calf thymus DNA in vitro was explored by fluorescence, resonance light scattering (RLS), UV-vis absorption, as well as viscometry, ionic strength effect and DNA melting techniques. It was found that SX could bind to DNA weakly, and the binding constants (Ka) were determined as 8.52×10(3), 8.31×10(3) and 6.14×10(3) L mol(-1) at 18, 28 and 38°C respectively. When bound to DNA, SX showed fluorescence quenching in the fluorescence spectra and hyperchromic effect in the absorption spectra. Stern-Volmer plots revealed that the quenching of fluorescence of SX by DNA was a static quenching. Furthermore, the relative viscosity and melting temperature of DNA solution were hardly influenced by SX, while the fluorescence intensity of SX-DNA was observed to decrease with the increasing ionic strength of system. Also, the binding constant between SX and double stranded DNA (dsDNA) was much weaker than that between SX and single stranded DNA (ssDNA). All these results suggested that the binding mode of SX to DNA should be groove binding. The obtained thermodynamic parameters indicated that electrostatic force might play a predominant role in SX binding to DNA. The quantum yield (φ) of SX was measured as 0.13 using comparative method. Based on the Förster resonance energy transfer theory (FRET), the binding distance (r0) between the acceptor and donor was calculated as 4.10 nm.
authors.affiliation: College of Chemistry, Changchun Normal University, Changchun 130032, China.
authors.forename: Tingting
authors.initials: T
authors.lastname: Zhao
authors.affiliation: College of Chemistry, Changchun Normal University, Changchun 130032, China. Electronic address: sy_bi@sina.com.
authors.forename: Shuyun
authors.initials: S
authors.lastname: Bi
authors.affiliation: College of Chemistry, Changchun Normal University, Changchun 130032, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.affiliation: College of Chemistry, Changchun Normal University, Changchun 130032, China.
authors.forename: Tianjiao
authors.initials: T
authors.lastname: Wang
authors.affiliation: TechnologyCenterofInspectionandQuarantine, Jilin Entry-Exit Inspection and Quarantine Bureau, Changchun 130062, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Pang
authors.affiliation: TechnologyCenterofInspectionandQuarantine, Jilin Entry-Exit Inspection and Quarantine Bureau, Changchun 130062, China.
authors.forename: Tingting
authors.initials: T
authors.lastname: Gu
mesh_terms: D000420:Albuterol / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008027:Light; D009691:Nucleic Acid Denaturation; D009994:Osmolar Concentration; D000068299:Salmeterol Xinafoate; D012542:Scattering, Radiation; D013050:Spectrometry, Fluorescence; D013696:Temperature; D013816:Thermodynamics; D014783:Viscosity
chemical_list: D000068299:Salmeterol Xinafoate; D004247:DNA; C427203:calf thymus DNA; D000420:Albuterol
keywords: DNA; Fluorescence; Groove binding; Resonance light scattering (RLS); Salmeterol xinafoate (SX)