title: G-quadruplex formation of thrombin-binding aptamer detected by electrospray ionization mass spectrometry.
abstract: Electrospray ionization mass spectrometry detected the formation of the G-quadruplex structure of the thrombin-binding aptamer, d(GGTTGGTGTGGTTGG), and established its specific interaction with metal ions. One piece of evidence that the bonding in the gas phase is via the G-quadruplex form is the enhanced binding, with respect to other metal ions, of the aptamer with Sr2+, Pb2+, Ba2+, and K+, which are of similar size. Another is the lack of specific binding with controls in which the G's are replaced with A's. The most convincing evidence is the extent of H/D exchange of the gas-phase aptamer as compared to that bound to K+ and Sr2+. The latter two complexes exchange six and nine fewer H's, indicating a significant increase in protection upon binding to the metals. Mass spectrometry will be an important tool in understanding G-quadruplexes, which are particularly important in DNA telomers.
authors.affiliation: Mass Spectrometry Research Resource, Department of Chemistry, Washington University, St. Louis, MO 63130, USA.
authors.forename: M
authors.initials: M
authors.lastname: Vairamani
authors.forename: Michael L
authors.initials: ML
authors.lastname: Gross
mesh_terms: D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D006147:Guanine / Q000737:chemistry* / Q000378:metabolism; D008670:Metals / Q000737:chemistry / Q000378:metabolism; D009838:Oligodeoxyribonucleotides / Q000737:chemistry* / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D013379:Substrate Specificity; D013917:Thrombin / Q000737:chemistry* / Q000378:metabolism
chemical_list: D008670:Metals; D009838:Oligodeoxyribonucleotides; D006147:Guanine; D004247:DNA; D013917:Thrombin