title: The study of binding of methyl tert-butyl ether to human telomeric G-quadruplex and calf thymus DNA by gas chromatography, a thermodynamic discussion.
abstract: Methyl-tert-butyl ether (MTBE) is widely used as an antiknock additive for increasing octane number of gasoline. Recently, the in vivo studies demonstrated that MTBE has genotoxic potential and able to form adducts with DNA. In the work, the interactions of MTBE with calf thymus DNA (ct-DNA) and the Na(+) form of G-quadruplex DNA (wtTel22) were studied by using of head space-solid phase microextraction technique coupled to gas chromatography. The binding equilibrium constants were measured through the equilibriums of a four phase system. In addition, the MTBE Henry's law constants for two different buffers in the temperature range of 283-303K were measured. Thermodynamic studies revealed that the complexation of MTBE to both DNAs is enthalpy favored and entropy disfavored. The thermodynamic results revealed that MTBE may have interaction with ct-DNA via the minor groove of DNA. Also, MTBE may be complexed into the basket of G-quadruplex structure. In addition, the low difference in the binding constants of MTBE for both different DNA targets may confirm that MTBE is poorly selective for different conformations of DNA.
authors.affiliation: Novel Drug Delivery Research Center, Faculty of Pharmacy, Kermanshah University of Medical Sciences, Kermanshah, Islamic Republic of Iran; Department of Medicinal Chemistry, Faculty of Pharmacy, Kermanshah University of Medical Sciences, Kermanshah, Islamic Republic of Iran.
authors.forename: Sahar
authors.initials: S
authors.lastname: Ghasemi
authors.affiliation: Novel Drug Delivery Research Center, Faculty of Pharmacy, Kermanshah University of Medical Sciences, Kermanshah, Islamic Republic of Iran; Department of Medicinal Chemistry, Faculty of Pharmacy, Kermanshah University of Medical Sciences, Kermanshah, Islamic Republic of Iran. Electronic address: fahmadi@kums.ac.ir.
authors.forename: Farhad
authors.initials: F
authors.lastname: Ahmadi
mesh_terms: D000818:Animals; D002417:Cattle; D002849:Chromatography, Gas / Q000379:methods*; D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D054856:G-Quadruplexes; D006801:Humans; D008738:Methyl Ethers / Q000737:chemistry / Q000378:metabolism*; D016615:Telomere / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D008738:Methyl Ethers; C043243:methyl tert-butyl ether; D004247:DNA; C427203:calf thymus DNA
keywords: Calf thymus DNA; Gas chromatography; Human telomeric G-quadruplex; Methyl-tert-butyl ether; Solid phase microextraction; Thermodynamic parameters