Protein oxidation species

The pathway of the metabolic process converting the original nutrients, which are of rather complex composition, to the simple end products of COj and HjO is long and complicated and consists of a large number of intermediate steps. Many of them are associated with electron and proton (or hydrogen-atom) transfer from the reduced species of one redox system to the oxidized species of another redox system. These steps as a rule occur, not homogeneously (in the cytoplasm or intercellular solution) but at the surfaces of special protein molecules, the enzymes, which are built into the intracellular membranes. Enzymes function as specific catalysts for given steps. 

The reactive oxygen species involved with protein oxidation can be generally categorized according to their relative reactivity as follows ... 

Two current alternative views are available as to how remotely boimd NADPH may work. One sees its action as involving two successive one-electron oxidations (52, 53). The effectiveness of NADPH in preventing compound II formation is then due to the high reactivity of the NADP intermediate as reductant of the compound II generated in the first one-electron step. The other model (47) prefers to see NADPH as a hydride donor responsible for the almost simultaneous reduction of the ferryl iron and the protein radical species. 

Semen, reactive oxygen species, 612 Sensorial quaUty appreciation, oxidation stabihty, 664 Semm protein oxidative damage, 614 see also Human seram Sesquiterpenes, stractural chemistry, 133-6 SET see Single electron transfer Sharpless epoxidation, allylic alcohols, 789 Shelf durability, peroxide value, 656 Ship-in-the-bottle strategy, chiral dioxetane synthesis, 1176-7... 

In in vitro studies the oxidation of LDL by endothelial cells, macrophage and Cu can be inhibited by a wide range of polyphenols and polyphenol-rich extracts [162-164]. Such effects may be due to polyphenols by direct scavenging of the oxidizing species, by regeneration of a-tocopherol in LDL [165], by their ability in binding metal ion and LDL protein [166]. 

A simple explanation of the failure of previous studies to detect any differences could be as a result of these studies not evaluating the relevant markers for health. Four of the markers (except lymphocyte proliferative capacity) can be assessed non-invasively (sleep, accumulation of adipose tissue) or in blood samples (IgA, protein oxidation), and are therefore suitable for use in human studies. In addition, all the markers can be assessed on a range of different animal species. 

Hawkins CL, Davies MJ (2005) The Role of Reactive V-Bromo Species and Radical Intermediates in Hypobromous Acid-Induced Protein Oxidation. Free Radic Biol Med 39 900... 

Arsenic has been shown to induce oxidative stress (Shi, Shi and Liu, 2004 Hughes and Kitchin, 2006). Oxidative stress is a result of an imbalance between reactive oxygen species and the ability of a cell s antioxidant defense apparatus to respond. Oxidative stress can result in the damage of proteins, lipids, RNA, and deoxyribonucleic acid (DNA). In addition, since oxidant species have a role in cell signaling, a state of oxidative stress could potentially alter signaling within and between cells. 

The impairment of glucose utilization could result from the modification of the glycolytic enzymes under oxidative stress effects. Oxidative stress is an important factor leading to the pathophysiologcal alterations in conformational diseases. Oxidative stress is manifested in protein oxidation, lipid peroxidation, DNA oxidation, and advanced glycation end-products, as well as reactive oxygen species (ROS), and reactive nitrogen species (RNS) formation. Either the oxidants or the products of oxidative stress could modify the proteins or activate other pathways that may lead to additional impairment of cellular functions and to neuronal loss [57, 58]. 

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