Title
Hg(II) Interactions with T-rich Regions in Oligonucleotides: Effects of Positional Variations on the Electrochemical Properties.
Author
Ajar Kamal, Renu Sharma, Zhe She, Heinz-Bernhard Kraatz
Year
2018
Journal
Analyst
Abstract
Hg(II) binding to thymine-rich oligonucleotides (ODNs) is investigated electrochemically. The focus of this study is to probe the effects of position on the electrochemical response. For this purpose, three oligonucleotides were investigated in which the position of a hexa-thymine repeat is varied within surface-supported oligonucleotide. The hexa repeats were placed in the top, middle, and bottom positions within the strand with respect to the gold surface. The effects were monitored by electrochemical impedance spectroscopy and by scanning electrochemical microscopy. Using charge transfer resistance (RCT) and tip current (I) as a measure, it was possible to monitor the effects of Hg(II) binding to the ds-oligonucleotide. The extent of film resistance reduces as the T-rich region moves from bottom to top position within the film. The T-rich region closer to gold surface probably build the less flexible and more rigid T-Hg(II)-T basepairs as compared to other two positions and expected to stay in the upright orientation on the surface. This in turn results in significant differences of the electrochemical readout, demonstrating that the position of T-rich sequences within an oligonucleotide strand matters.
Instrument
J-815
Keywords
Circular dichroism, DNA structure, Ligand binding, Biochemistry