Quadruplex-to-Duplex Transition of G-Rich Oligonucleotides Probed by Cationic Water-Soluble Conjugated Polyelectrolytes

• Published in: Journal of the American Chemical Society Vol. 128; no. 21; pp. 6764 - 6765
• Main Authors: He, Fang, Tang, Yanli, Yu, Minghui, Feng, Fude, An, Lingling, Sun, Huan, Wang, Shu, Li, Yuliang, Zhu, Daoben, Bazan, Guillermo C
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 31.05.2006
• Subjects: Biological and medical sciences; Cations; Conformational dynamics in molecular biology; DNA - chemistry; Electrolytes - chemistry; Fluorescein - chemistry; Fundamental and applied biological sciences. Psychology; Guanine - chemistry; Molecular biophysics; Nucleic Acid Conformation; Oligonucleotides - chemistry; Solubility; Spectrometry, Fluorescence; Water; Polyelectrolyte; Conjugated polymer; Double stranded DNA; Light harvesting system; Resonance energy; Oligonucleotide; Aqueous solution; Conformational changes; Energy transfer; Duplex; Fluorescence spectrometry; Conformational transition
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja058075w

G-quartet DNA converts to duplex form in the presence of its complementary strand. This conformational change can be detected in real time by a homogeneous assay method based on the signal amplification of conjugated polyelectrolytes and the specific interaction of intercalating dyes with double-stranded DNA (dsDNA). The probe solution contains a cationic, conjugated polymer (CCP), G-quadruplex labeled with a fluorescein at the 5‘-terminus (G-quadruplex-Fl), and ethidium bromide (EB). The addition of a complementary target results in the transition from G-quadruplex to duplex (dsDNA-Fl) and EB intercalation within the duplex structure. Excitation of the CCP leads to energy transfer from CCP to dsDNA-Fl (FRET-1) and then energy transfer from dsDNA-Fl to EB (FRET-2). Increasing the number of mismatched bases discourages dsDNA formation, which is detected in the assay.