title: Discrimination of G-quadruplexes from duplex and single-stranded DNAs with fluorescence and energy-transfer fluorescence spectra of crystal violet.
abstract: G-rich nucleic acid sequences with the potential to form G-quadruplex structures are common in biologically important regions. Most of these sequences are present with their complementary strands, so the development of a sensitive biosensor to distinguish G-quadruplex and duplex structures and to determine the competitive ability of quadruplex to duplex structures has received a great deal of attention. In this work, the interactions between two triphenylmethane dyes (malachite green (MG) and crystal violet (CV)) and G-quadruplex, duplex, or single-stranded DNAs were studied by fluorescence spectroscopy and energy-transfer fluorescence spectroscopy. Good discrimination between quadruplexes and duplex or single-stranded DNAs can be achieved by using the fluorescence spectrum of CV or the energy-transfer fluorescence spectra of CV and MG. In addition, by using energy-transfer fluorescence titrations of CV with G-quadruplexes, the binding-stoichiometry ratios of CV to G-quadruplexes can be determined. By using the fluorescence titrations of G-quadruplex-CV complexes with C-rich complementary strands, the fraction of G-rich oligonucleotide that engages in G-quadruplex structures in the presence of the complementary sequence can be measured. This study may provide a simple method for discrimination between quadruplexes and duplex or single-stranded DNAs and for measuring G-quadruplex percentages in the presence of the complementary C-rich sequences.
authors.affiliation: Key Laboratory of Functional Polymer Materials, Ministry of Education, Nankai University, Tianjin, China. kongdem@nankai.edu.cn
authors.forename: De-Ming
authors.initials: DM
authors.lastname: Kong
authors.forename: Yong-E
authors.initials: YE
authors.lastname: Ma
authors.forename: Jing
authors.initials: J
authors.lastname: Wu
authors.forename: Han-Xi
authors.initials: HX
authors.lastname: Shen
mesh_terms: D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry*; D004277:DNA, Single-Stranded / Q000737:chemistry*; D004735:Energy Transfer; D005456:Fluorescent Dyes / Q000737:chemistry*; D054856:G-Quadruplexes / Q000528:radiation effects; D005840:Gentian Violet / Q000737:chemistry*; D009841:Oligonucleotides / Q000737:chemistry; D013050:Spectrometry, Fluorescence
chemical_list: D004277:DNA, Single-Stranded; D005456:Fluorescent Dyes; D009841:Oligonucleotides; D004247:DNA; D005840:Gentian Violet