Hydrogen peroxide protein oxidation

Tyramide signal amplification This procedure, designated as a catalyzed reporter deposition (CARD) or tyramide signal amplification (TSA), takes advantage of horseradish peroxidase (HRP) from an HRP-labeled secondary antibody to catalyze in the presence of hydrogen peroxide the oxidation of the phenol moiety of labeled tyramine. On oxidation by HRP, activated tyramine molecules rapidly bind covalently to electron-rich amino acids of proteins immediately surrounding the site of the immunoreaction. This allows an increase in the detection of an antigenic site up to 100-fold compared with the conventional indirect method with no loss in resolution. 

Hambly, D.M. Gross, M.L. Laser flash photolysis of hydrogen peroxide to oxidize protein solvent-accessible residues on the microsecond timescale. J. Am. Soc. Mass Spectrom. 

Peroxidases oxidize tyrosines, both as a free amino acid and as a residue in peptides and proteins. When proteins are treated with HRP in the presence of hydrogen peroxide, protein dimers are obtained through the coupling of tyrosyl radicals. HRP can also be used for cross-linking of proteins with polysaccharides [35]. In this case, coupling occurs between a tyrosyl radical in the protein and a radical species on the saccharide ... 

Hambly, D.M., Gross, M.L. (2005) Laser Hash Photolysis of Hydrogen Peroxide to Oxidize Protein Solvent-Accessible Residues on the Microsecond Timescale. Journal of the American Society for Mass Spectrometry, 16 (12), 2057-2063. 

You can bleach hair by using hydrogen peroxide to oxidize these colored pigments to their colorless forms. However, bleached hair becomes weaker and more brittle, because the hair protein is broken down into lower molecular weight compounds. Perborate compounds, which tend to be more expensive than bleach, and chlorine-based bleaches are also sometimes used to bleach hair. 

In search of alternatives to Chloramine-T, Morrison (1980) demonstrated that lactoperoxidase from bovine milk was particularly effective for iodide oxidation and the radioiodination of proteins. The single strand polypeptide lactoperoxidase has a molecular weight of approximately 78 kD. The structure of lactoperoxidase contains a prosthetic heme group which is covalently linked to the protein at the active site of the enzyme. In the presence of minute quantities of hydrogen peroxide, lactoperoxidase oxidizes and binds radioiodide to proteins in the reaction mixture. The pH optimum of iodide oxidation by lactoperoxidase is 4-8.5 with an optimum at pH 5. The reaction is extremely rapid, allowing reaction times of less than 1 min. This provides very mild conditions and denaturation of proteins is low. Yields of up to 85% can be obtained and the method is widely used for labeling proteins and hormones. Lactoperoxidase may itself... 

DNA damage was assessed in human umbihcal vein endothelial cells exposed to superoxide, hydrogen peroxide, nitric oxide, and peroxynitrite (Ballinger etal. 2000). In both vascular endotheUal and human aortic smooth muscle cells, the mitochondrial DNA was preferentially damaged relative to the transcriptionally inactive nuclear P-globulin gene. Similarly, a dose-dependent decrease in mtDNA-encoded mRNA transcripts was associated with reactive species treatment. Mitochondrial protein synthesis was also inhibited in a dose-dependent manner by peroxynitrite, resulting in decreased cellular ATP levels and mitochondrial redox function. 

What prompted the present study was our recent discovery that the protein carbonyl allysine (adipic semialdehyde) can become further oxidized into 2-aminoadipic acid (2-AAA) (see Scheme I). In human skin, this thermodynamically stable oxidation endproduct of lysine, accumulated to a much larger extent than its precursor measured as 6-hydroxynorleucine. This finding implied that hydrogen peroxide mediated oxidation was important in the extracellular matrix and raised the question whether intracellular long-lived proteins, such as the crystallins were also subject to lysyl oxidation and 2-AAA formation. 

One of the important consequences of neuronal stimulation is increased neuronal aerobic metabolism which produces reactive oxygen species (ROS). ROS can oxidize several biomoiecules (carbohydrates, DNA, lipids, and proteins). Thus, even oxygen, which is essential for aerobic life, may be potentially toxic to cells. Addition of one electron to molecular oxygen (O,) generates a free radical [O2)) the superoxide anion. This is converted through activation of an enzyme, superoxide dismurase, to hydrogen peroxide (H-iO,), which is, in turn, the source of the hydroxyl radical (OH). Usually catalase... 

Other examples are the use of osmium(VIII) oxide (osmium tetroxide) as catalyst in the titration of solutions of arsenic(III) oxide with cerium(IV) sulphate solution, and the use of molybdate(VI) ions to catalyse the formation of iodine by the reaction of iodide ions with hydrogen peroxide. Certain reactions of various organic compounds are catalysed by several naturally occurring proteins known as enzymes. 

Several powerful oxidants are produced during the course of metabolism, in both blood cells and most other cells of the body. These include superoxide (02 ), hydrogen peroxide (H2O2), peroxyl radicals (ROO ), and hydroxyl radicals (OH ). The last is a particularly reactive molecule and can react with proteins, nucleic acids, lipids, and other molecules to alter their structure and produce tissue damage. The reactions listed in Table 52-4 play an important role in forming these oxidants and in disposing of them each of these reactions will now be considered in turn. 

---