title: Hemin/G-quadruplex structure and activity alteration induced by magnesium cations.
abstract: The influence of metal cations on G-quadruplex structure and peroxidase-mimicking DNAzyme activity was investigated. Experiments revealed a significant role of magnesium ion, which in the presence of potassium cation influenced DNAzyme activity. This ability has been associated with alteration of G-quadruplex topology and consequently affinity to bind hemin molecule. It has been demonstrated that G-quadruplex based on PS2.M sequence under these conditions formed parallel topology, which exhibited lower activity than that observed in standard potassium-containing solution. On the other hand DNAzyme/magnesium ion system based on telomeric sequence, which did not undergo significant structural changes, exhibited higher peroxidase activity upon magnesium ion addition. In both cases, the stabilization effect of magnesium cations on G-quadruplex structure was observed. The mechanism of DNAzyme activity alteration by magnesium ion can be explained by its influence on the pKa value of DNAzyme. Magnesium ion decreased pKa for PS2.M based system but increased it for telomeric DNAzyme. Magnesium cation effect on G-quadruplex structure as well as DNAzyme activity is particularly important since this ion is one of the most common metal cations in biological samples.
authors.affiliation: Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89b, 61-614 Poznan, Poland. Electronic address: kosman@amu.edu.pl.
authors.forename: J
authors.initials: J
authors.lastname: Kosman
authors.affiliation: Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89b, 61-614 Poznan, Poland.
authors.forename: B
authors.initials: B
authors.lastname: Juskowiak
mesh_terms: D002412:Cations / Q000737:chemistry*; D021881:DNA, Catalytic / Q000737:chemistry; D004789:Enzyme Activation; D054856:G-Quadruplexes; D006427:Hemin / Q000737:chemistry*; D007700:Kinetics; D008274:Magnesium / Q000737:chemistry*; D008968:Molecular Conformation; D011188:Potassium / Q000737:chemistry; D012964:Sodium / Q000737:chemistry; D013329:Structure-Activity Relationship; D013696:Temperature
chemical_list: D002412:Cations; D021881:DNA, Catalytic; D006427:Hemin; D012964:Sodium; D008274:Magnesium; D011188:Potassium
keywords: DNAzyme; G-quadruplex; Peroxidase activity