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Zn Ions Change Binding Mode of TOEPyP4 with DNA and Cause DNA Transition from B to C and Zn-Like Conformations

It is known that at low concentrations of TMPyP4, this porphyrin predominantly intercalates between GC pairs at GC-rich sites of duplex DNA and G-quadruplexes of various constructions, and stabilizes these structures. However, there are still some arguable suggestions about the exact binding sites a...

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Bibliographic Details
Published in:American journal of analytical chemistry 2013-12, Vol.4 (12), p.744-748
Main Authors: Monaselidze, Jamlet, Gorgoshidze, Maya, Khachidze, David, Kiladze, Maya, Bregadze, Vasil, Kiziria, Eugene, Margaryan, Hakob, Hakobyan, Nune
Format: Article
Language:English
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Summary:It is known that at low concentrations of TMPyP4, this porphyrin predominantly intercalates between GC pairs at GC-rich sites of duplex DNA and G-quadruplexes of various constructions, and stabilizes these structures. However, there are still some arguable suggestions about the exact binding sites and modes of TMPyP4 to GC-rich regions of DNA in case of helation of divalent ions with help of the porphrin, which makes porphyrin structure asymmetric. We examined TOEPyP4-analogue of TMPyP4-and studied interaction of TOEPyP4 into the calf thymus DNA at presence of nanomole concentrations of one of the most important microelements in cell vital function-Zn ion. On the basis of CD and absorption spectra of the DNA-TOEPyP4 mixture, it was determined that nanomole concentrations of Zn ions changed porphyrin intercalative binding mode to some external binding modes, which initiated transition of the canonic B conformation of DNA into C-like conformation, and incubation of the (DNA-TOEP4) + Zn mixture at 37 degree C caused B-Z-like transition, but no transition was observed for the DNA-TOEPyP4 mixture. In particular, at 10 mM-NaCl, TOEPyP4/DNA = 0.02, the binding mode change was observed in the concentration range from 150 to 300 nM-Zn, and the B-C-like transition occurred from 150 to 600 nM-Zn. The B-Z transition at TOEPyP4/DNA = 0.015, Zn/DNA = 0.015, NaCI 10 mM, T = 37 degree C was observed within incubation time interval from 0.3 to 20 hours, and maximal percent of Z-like form was seen when incubation time interval was from 5 to 6 hours.
ISSN:2156-8251
2156-8278
DOI:10.4236/ajac.2013.412090