Title
A study of the interactions of Hg(II) with T-T mispair containing hairpin loops
Author
Ajar Kamal, Zhe She, Renu Sharma, Heinz-Bernhard Kraatz
Year
2017
Journal
Electrochimica Acta
Abstract
This manuscript describes the result of a series of electrochemical, spectroscopic and thermodynamic studies into oligonucleotide hairpin structures equipped with T-T mispairs and investigates their interaction with Hg(II). For this purpose, three hairpin DNAs were designed, in which the stem-region remains constant and loop region contains increasing T-T mispairs (5ʹ-HO-(CH2)6-S-S-(CH2)6-TGTAGTTCCTTCTACA-3ʹ, 5ʹ-HO-(CH2)6-S-S-(CH2)6-TGTAGTTTTCCTTTTCTACA-3ʹ; 5ʹ-HO-(CH2)6-S-S-(CH2)6-TGTAGTTTTTTCCTTTTTTCTACA-3ʹ). Various techniques such as electrochemical impedance spectroscopy (EIS), circular dichroism (CD), UV-visible and isothermal titration calorimetry (ITC) were employed to get a systematic evaluation of the need for multiple T-T mispairs for enhanced Hg(II) binding. EIS shows an increase in charge transfer resistance (ΔRCT) due to structural changes within the thin film caused by Hg(II) binding. The CD studies indicate the Hg(II) induced changes in CD signals of hairpin DNAs from right-handed to left handed structures. Highest cooperative binding was observed with DNA having maximum T-T mispairs which was supplemented by detailed UV-visible thermal analysis of DNA-Hg(II) structures. These findings were further supported by detailed measurements of the thermochemistry of the interaction by ITC. Our studies show that the number of T-T mispairs are critical for maximizing nucleobase-Hg(II) interactions.
Instrument
J-815
Keywords
Circular dichroism, DNA structure, Ligand binding, Biochemistry