title: Spectral properties and thermal stability of AS1411 G-quadruplex.
abstract: G-quadruplexes are supramolecular structures of G-rich nucleic acid, formed by non-canonical base pairing in the presence of specific environmental inducers. These structures have been vastly considered in diagnostic and therapeutic applications. However, detailed information on structure, optical properties and thermal stability of G-quadruplex potent oligonucleotides is scarce. Herein, optical properties and thermodynamic stability of AS1411 quadruplex is reported for various concentrations of potassium and lead ions. Circular dichroism showed that AS1411 ss-DNA folds into parallel conformation in the presence of metal ions and molecular crowding condition. UV-vis spectroscopy indicated formation of quadruplex and fluorescent spectroscopy revealed intercalation of PicoGreen in its structure, with enhancement of emission intensity upon increment of metal ion concentration. This investigation also proposes high-throughput and reliable analysis of AS1411 quadruplex's thermal stability by real-time PCR technique, which can be further applied for other quadruplex structures.
authors.affiliation: Department of Biophysics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran.
authors.forename: Zeinab
authors.initials: Z
authors.lastname: Bagheri
authors.affiliation: Department of Biophysics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran; Department of Nanobiotechnology, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran. Electronic address: ranjbarb@modares.ac.ir.
authors.forename: Bijan
authors.initials: B
authors.lastname: Ranjbar
authors.affiliation: Laser and Plasma Research Institute, Shahid Beheshti University, Evin, Tehran, Iran. Electronic address: latifi@sbu.ac.ir.
authors.forename: Hamid
authors.initials: H
authors.lastname: Latifi
authors.affiliation: Laser and Plasma Research Institute, Shahid Beheshti University, Evin, Tehran, Iran.
authors.forename: Mohammad Ismail
authors.initials: MI
authors.lastname: Zibaii
authors.affiliation: Department of Nanobiotechnology, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran.
authors.forename: Tahereh Tohidi
authors.initials: TT
authors.lastname: Moghadam
authors.affiliation: Department of Biophysics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran.
authors.forename: Azade
authors.initials: A
authors.lastname: Azizi
mesh_terms: D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D021881:DNA, Catalytic / Q000737:chemistry; D054856:G-Quadruplexes; D009841:Oligonucleotides / Q000737:chemistry; D013816:Thermodynamics
chemical_list: D021881:DNA, Catalytic; D009841:Oligonucleotides; D004247:DNA
keywords: AS1411 aptamer; Circular dichroism; G-quadruplex; Thermal stability