Effects of Complex Formation of DNA with Positively Charged Polyamines and Polypeptides on the Products of Oxidative Damage to DNA 2-Deoxyribose by Hydroxyl Radicals

It is known that histones and other DNA-binding polycations protect DNA from radiation damage mediated by hydroxyl radicals. Until recently, this protection of DNA has mainly been attributed to compaction and aggregation. It was hypothesized that chemical repair of DNA sugar radicals by donation of hydrogen atom from polycations also significantly contributes to DNA protection. To test this hypothesis, the relative yields of low-molecular weight characteristic products of oxidation of DNA sugar were compared in X-irradiated samples of naked DNA and DNA complexes with a number of polycations by using an HPLC-based method of DNA damage product quantification. The variation in the percent contribution of the C1„ sugar damage product ongoing from free DNA to DNA-polycations complexes is in agreement with the hypothesis that chemical repair of DNA sugar radicals by donation of hydrogen atom from polycations contributes to the overall DNA protection against hydroxyl radical-mediated damage

Association with Polyamines and Polypeptides Increases the Relative Yield of 2-Deoxyribonolactone Lesions in Radiation-Damaged DNA

The production of 2-deoxyribonolactones (C1\u27-oxidation product), C4\u27-oxidized abasic sites and C5\u27-carbonyl terminated strand scission products was investigated in complexes of double-stranded DNA with protamine, poly-L-lysine and spermine exposed to X-ray radiation. The lesions were quantified by high-performance liquid chromatography through the release of the corresponding low-molecular-weight products 5-methylenefuran-2(5H)-one, N-(2\u27-hydroxy-ethyl)-5-methylene-D3-pyrrolin-2-one and furfural, respectively. All binders were found to increase the relative yield of C1\u27 oxidation up to 40% of the total 2-deoxyribose damage through the indirect effect versus approximately 18% typically found in homogeneous solutions by the same technique. On the contrary, the yield of C5\u27-oxidation was found to be suppressed almost completely, while in homogeneous solutions it constituted approximately 14% of the total. The observed change in end product distribution is attributed to free valence transfer to and from the complexing agent, although the mechanisms associated with this process remain unclear

Electrochemical characterization of electrolyte purity for CO2 reduction studies

In this work, we put forward a simple electrochemical approach to conveniently determine the purity of the electrolyte solution which improves the reproducibility and reliability of electrochemical CO2 reduction data such that experimental outcomes can be readily compared across research groups. The method uses a polycrystalline Au electrode as a probe to detect electrolyte impurities that can readily be adsorbed to surfaces even when ultrahigh-purity (99.999%) commercial chemicals are used as received. Herein, we show how the extent of trace contamination alters the measured activity during CO2 reduction and demonstrate electrochemical methods to capture these trace contaminants, such that CO2 reduction activity can be reproduced reliably

The Role of Entropy on the Electrochemistry of Entropy-Stabilized Oxides and Their Lithium Storage Mechanism

Micrometer-size particles of entropy-stabilized transition metal-based high entropy oxide, (MgCoNiCuZn)O, has demonstrated long-term cycling stability against lithium-ion battery, a feat that has only been achieved with nanometer-size transition metal binary oxides. This electrochemical performance has been attributed to the entropy stabilization effect observed in this material. This work demonstrates that entropy stabilization might not play a role in the electrochemical performance of this compound as previously suggested, by comparing the electrochemical data of two medium entropy materials, (MgNiCuZn)O and (CoNiCuZn)O, with that of the high entropy material. In addition, the mechanism of lithium interaction with these materials is still poorly understood, in part owing to the difficulties in characterizing structure at the nanoscale. Solid-state operando NMR/derivative operando techniques are used to demonstrate that the lithiation of these compounds proceeds via a partially reversible conversion-type reaction involving the reduction of the transition metals cations to their metallic form during lithiation and the oxidation of these individual metal particles to their oxides form, losing the initial single-phase compound after the first lithiation cycle. The NMR results also show that the conductive carbon black used as an electronic conductor can store a significant amount of charge at low voltage, indicating that it is a major contributor to the additional observed in these entropy-stabilized oxides and in transition metal salts

A Guide to Evaluate Electrolyte Purity for CO₂ Reduction Studies

A Guide to Evaluate Electrolyte Purity for CO2 Reduction Studie