Redox

About: Redox is a research topic. Over the lifetime, 26853 publications have been published within this topic receiving 862368 citations. The topic is also known as: reduction-oxidation & reduction-oxidation reaction.

Redox Reactions of Hemoglobin and Myoglobin: Biological and Toxicological Implications

Abstract: Direct cytotoxic effects associated with hemoglobin (Hb) or myoglobin (Mb) have been ascribed to redox reactions (involving either one- or two-electron steps) between the heme group and peroxides. These interactions are the basis of the pseudoperoxidase activity of these hemoproteins and can be cytotoxic when reactive species are formed at relatively high concentrations during inflammation and typically lead to cell death. Peroxides relevant to biological systems include hydrogen peroxide, lipid hydroperoxides, and peroxynitrite. Reactions between Hb/Mb and peroxides form the ferryl oxidation state of the protein, analogous to compounds I and II formed in the catalytic cycle of many peroxidase enzymes. This higher oxidation state of the protein is a potent oxidant capable of promoting oxidative damage to most classes of biological molecules. Free iron, released from Hb, also has the potential to promote oxidative damage via classical "Fenton" chemistry. It has become increasingly evident that Hb/Mb redox reactions or their by-products play a critical role in the pathophysiology of some disease states. This review briefly discusses the reactions of Hb/Mb with biological peroxides, potential cytotoxicity and the impact of these interactions on modulation of cell signaling pathways regulated by these reactive species. Also discussed in this article is the role of heme-protein chemistry in relation to the toxicity of hemoproteins.

Mechanisms of cytochrome P450 substrate oxidation: MiniReview.

Abstract: Cytochrome P450 (P450) enzymes catalyze a variety of oxidation and some reduction reactions, collectively involving thousands of substrates. A general chemical mechanism can be used to rationalize most of the oxidations and involves a perfenyl intermediate (FeO3+) and odd-electron chemistry, i.e. abstraction of a hydrogen atom or electron followed by oxygen rebound and sometimes rearrangement. This general mechanism can explain carbon hydroxylation, heteroatom oxygenation and dealkylation, epoxidation, desaturation, heme destruction, and other reactions. Another approach to understanding catalysis involves analysis of the more general catalytic cycle, including substrate specificity, because complex patterns of cooperativity are observed with several P450s. Some of the complexity is due to slow conformational changes in the proteins that occur on the same timescale as other steps.

Intermediate honeycomb ordering to trigger oxygen redox chemistry in layered battery electrode

Abstract: Sodium-excess metal oxides Na2MO3 are appealing cathode materials for sodium-ion batteries. Here, the authors demonstrate that honeycomb-type cation ordering in Na2RuO3 triggers the oxygen redox reaction via frontier orbital reorganization, increasing the capacity by 1/3 compared with disordered Na2RuO3.