title: Conformation-dependent exonuclease III activity mediated by metal ions reshuffling on thymine-rich DNA duplexes for an ultrasensitive electrochemical method for Hg2+ detection.
abstract: Hg(2+) is known to bind very strongly with T-T mismatches in DNA duplexes to form T-Hg(2+)-T base pairs, the structure of which is stabilized by covalent N-Hg bonds and exhibits bonding strength higher than hydrogen bonds. In this work, we exploit exonuclease III (Exo III) activity on DNA hybrids containing T-Hg(2+)-T base pairs and our experiments show that Hg(2+) ions could intentionally trigger the activity of Exo III toward a designed thymine-rich DNA oligonucleotide (e-T-rich probe) by the conformational change of the probe. Our sensing strategy utilizes this conformation-dependent activity of Exo III, which is controlled through the cyclical shuffling of Hg(2+) ions between the solution phase and the solid DNA hybrid. This interesting attribute has led to the development of an ultrasensitive detection platform for Hg(2+) ions with a detection limit of 0.2 nM and a total assay time within minutes. This simple detection strategy could be used for the detection of other metal ions which exhibit specific interactions with natural or synthetic bases.
authors.affiliation: Department of Chemical and Biomolecular Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
authors.forename: Feng
authors.initials: F
authors.lastname: Xuan
authors.forename: Xiaoteng
authors.initials: X
authors.lastname: Luo
authors.forename: I-Ming
authors.initials: IM
authors.lastname: Hsing
mesh_terms: D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D055664:Electrochemical Techniques; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000032:analysis* / Q000494:pharmacology; D005090:Exodeoxyribonucleases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D008628:Mercury / Q000032:analysis* / Q000494:pharmacology; D013329:Structure-Activity Relationship; D013941:Thymine / Q000031:analogs & derivatives / Q000737:chemistry* / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D004247:DNA; D005090:Exodeoxyribonucleases; C020133:exodeoxyribonuclease III; D008628:Mercury; D013941:Thymine