Extra Copper‐mediated Enhancement of the DNA Cleavage Activity Supported with Wild‐type Cu, Zn Superoxide Dismutase

Abstract

It is well known that the primary function of wild type Cu, Zn superoxide dismutase (holo SOD) is to catalyze the conversion of the superoxide anion to H 2 O 2 and O 2 as an antioxidant enzyme. However, the aberrant copper-mediated oxidation chemistry in the enzyme (including its mutation forms) that damages nucleic acids, proteins including itself and cell membrane has attracted extensive attention in the past decade. The present study examined the hydrogen peroxide-dependent DNA cleavage activity supported with the combinations between holo SOD and extra copper (holo SOD＋nCu(II)). The results indicate that the presence of extra copper can enhance the DNA cleavage activity and a cooperative effect between holo SOD and the extra Cu(II) occurs in DNA cleavage. The relative activity and kinetic assay showed that the DNA cleavage activity of holo SOD＋nCu(II) was enhanced upon addition of extra Cu(II). The favorable pH regions for the DNA cleavage were observed to be 3.6-5.6 and 9.0-10, suggesting the species responsible for the DNA cleavage are different in different pH regions. In addition, to obtain an insight into DNA cleavage pathways, the effect of free radical scavengers and inhibitors on the DNA cleavage activity was probed.

Controllable Acid/Base Propriety of Sulfate Modified Mixed Metal Oxide Derived from Hydrotalcite for Synthesis of Propylene Carbonate

“…A series of catalysts with different acidity and basicity were prepared and fully characterized in this investigation. The results revealed that the introduction of sulfur significantly affected the acidity and alkalinity of the oxide surface [28][29][30]. However, different from the same reaction catalyzed by fluorinated MgAlO (MgAlO-F) under high pressure [31], the MgAl bilayer oxide modified by sulfate could promote the reaction more efficiently and can operate with mild conditions.…”