title: Detection of Naja atra Cardiotoxin Using Adenosine-Based Molecular Beacon.
abstract: This study presents an adenosine (A)-based molecular beacon (MB) for selective detection ofNaja atracardiotoxin (CTX) that functions by utilizing the competitive binding between CTX and the poly(A) stem of MB to coralyne. The 5'- and 3'-end of MB were labeled with a reporter fluorophore and a non-fluorescent quencher, respectively. Coralyne induced formation of the stem-loop MB structure through A₂-coralyne-A₂ coordination, causing fluorescence signal turn-off due to fluorescence resonance energy transfer between the fluorophore and quencher. CTX3 could bind to coralyne. Moreover, CTX3 alone induced the folding of MB structure and quenching of MB fluorescence. Unlike that of snake venom α-neurotoxins, the fluorescence signal of coralyne-MB complexes produced a bell-shaped concentration-dependent curve in the presence of CTX3 and CTX isotoxins; a turn-on fluorescence signal was noted when CTX concentration was ≤80 nM, while a turn-off fluorescence signal was noted with a further increase in toxin concentrations. The fluorescence signal of coralyne-MB complexes yielded a bell-shaped curve in response to varying concentrations ofN. atracrude venom but not those ofBungarus multicinctusandProtobothrops mucrosquamatusvenoms. Moreover,N. nigricollisvenom also functioned asN. atravenom to yield a bell-shaped concentration-dependent curve of MB fluorescence signal, again supporting that the hairpin-shaped MB could detect crude venoms containing CTXs. Taken together, our data validate that a platform composed of coralyne-induced stem-loop MB structure selectively detects CTXs.
authors.affiliation: Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan. a786514@gmail.com.
authors.forename: Yi-Jun
authors.initials: YJ
authors.lastname: Shi
authors.affiliation: Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan. yjchen@mail.nsysu.edu.tw.
authors.forename: Ying-Jung
authors.initials: YJ
authors.lastname: Chen
authors.affiliation: Department of Biotechnology, Kaohsiung Medical University, Kaohsiung 807, Taiwan. wphu@cc.kmu.edu.tw.
authors.forename: Wan-Ping
authors.initials: WP
authors.lastname: Hu
authors.affiliation: Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan. lschang@mail.nsysu.edu.|Department of Biotechnology, Kaohsiung Medical University, Kaohsiung 807, Taiwan. lschang@mail.nsysu.edu.
authors.forename: Long-Sen
authors.initials: LS
authors.lastname: Chang
mesh_terms: D000241:Adenosine / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D001600:Berberine Alkaloids / Q000737:chemistry / Q000378:metabolism*; D001667:Binding, Competitive; D015374:Biosensing Techniques; D004179:Cobra Cardiotoxin Proteins / Q000737:chemistry / Q000378:metabolism*; D017815:Elapidae; D031541:Fluorescence Resonance Energy Transfer; D062105:Molecular Docking Simulation; D015394:Molecular Structure; D011108:Polymers / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding
chemical_list: D001600:Berberine Alkaloids; D004179:Cobra Cardiotoxin Proteins; D011108:Polymers; C069424:polyadenosine; C000666:coralyne; D000241:Adenosine
keywords: cardiotoxin; coralyne; molecular beacon; polyadenosine; snake venom