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Imidazole-modified G-quadruplex DNA as metal-triggered peroxidase

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Abstract

Four imidazoles, serving as metalloprotein-inspired ligands for complexing a range of transition metal cations, were incorporated into tetramolecular G-quadruplex DNA structures. Modified quadruplexes were found to complex Cu(II), Ni(II), Zn(II) and Co(II) in a 1 : 1 ratio with unprecedented strong thermal stabilizations of up to ΔT1/2 = +51 °C. Furthermore, addition of Cu(II) was found to lead to extraordinarily fast G-quadruplex association rates with kon values being ∼100 times higher compared to unmodified G-quadruplexes. This is ascribed to a template effect of Cu(II), preorganizing the four single strands via coordination, followed by rapid formation of hydrogen-bonded G-quartets. Native electrospray ionization mass spectrometry (ESI), coupled with trapped ion-mobility spectrometry (timsTOF), supports the proposed 1 : 1 G-quadruplex-metal complexes and could further disclose their ability to bind the iron–porphyrin complex hemin in a 1 : 1 stoichiometry. DNA sequence design allowed us to equip this G-quadruplex-hemin complex, known to function as a horseradish peroxidase mimic, with a metal-dependent trigger. A competitive screen of transition metals revealed a high selectivity for Cu(II), even in mixtures of several divalent metal cations. Once formed, the Cu(II)-carrying DNAzyme was shown to be preserved in the presence of EDTA, attributed to its remarkable kinetic stability. Stimuli-responsive G-quadruplexes promise application in DNAzymes with switchable activity, adaptive sensors and dynamic DNA origami constructs.

Graphical abstract: Imidazole-modified G-quadruplex DNA as metal-triggered peroxidase

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Publication details

The article was received on 11 Nov 2018, accepted on 31 Dec 2018 and first published on 07 Jan 2019


Article type: Edge Article
DOI: 10.1039/C8SC05020A
Citation: Chem. Sci., 2019, Advance Article
  • Open access: Creative Commons BY license
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    Imidazole-modified G-quadruplex DNA as metal-triggered peroxidase

    Philip M. Punt and G. H. Clever, Chem. Sci., 2019, Advance Article , DOI: 10.1039/C8SC05020A

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