Quadruplex-to-duplex transition of G-rich oligonucleotides probed by cationic water-soluble conjugated polyelectrolytes.
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.
He
Fang
F
Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, P.R. China.
Tang
Yanli
Y
Yu
Minghui
M
Feng
Fude
F
An
Lingling
L
Sun
Huan
H
Wang
Shu
S
Li
Yuliang
Y
Zhu
Daoben
D
Bazan
Guillermo C
GC
D002412:Cations; D004247:DNA / Q000737:chemistry*; D004573:Electrolytes / Q000737:chemistry; D019793:Fluorescein / Q000737:chemistry; D006147:Guanine / Q000737:chemistry; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000737:chemistry*; D012995:Solubility; D013050:Spectrometry, Fluorescence; D014867:Water
D002412:Cations; D004573:Electrolytes; D009841:Oligonucleotides; D014867:Water; D006147:Guanine; D004247:DNA; D019793:Fluorescein