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Reactivities of Amino Acids and Proteins with Iodine
Published in Erwin Regoeczi, Iodine-Labeled Plasma Proteins, 2019
Oxidation to the reversible methionine sulfoxide stage occurs with a range of agents. They are not specific for methionine, though they may act more or less selectively depending on the reaction conditions (pH, time, concentration, and the presence or absence of certain other amino acid residues). Periodate rapidly oxidizes methionine in a protein, but it also oxidizes cysteine, cystine, histidine, tryptophan, and tyrosine, in addition to N-terminal serine and threonine.40 Hydrogen peroxide preferentially oxidizes methionine in chymotrypsin,41,42 chymotrypsinogen,42 and ribonuclease43 at low pH (pH 2 to 3); H2O2 selectively oxidizes methionine in bovine and sheep growth hormones both at pH 2.85 and 8.5,44 and in subtilisin at pH 8.8.4S Alkyl hydroperoxides are less active oxidants of methionine than is hydrogen peroxide.46 Methionines in growth hormone are also effectively oxidized at PH 7.4 by chloramine-T.47 In addition, chloramine-T is selectively active on methionines in the bacterial protein, flagellin, from Salmonella adelaide at pH 7.0.48 According to Shechter and colleagues,49 chloramine-T, at neutral and slightly alkaline pH values, is a selective oxidizing agent of methionyl residues in those proteins which are devoid of free sulfhydryl groups.
Superoxide Dismutase, Mitochondrial Dysfunction, and Neurodegenerative Diseases
Published in Shamim I. Ahmad, Handbook of Mitochondrial Dysfunction, 2019
Jahaun Azadmanesh, Gloria E. O. Borgstahl
ONOO– can also inactivate proteins through reaction with amino acids. For example, ONOO– can oxidize critical cysteine active site residues of enzymes and inactivate catalysis. Inactivation of tyrosine phosphatases by ONOO– oxidation is especially noteworthy [26], as this foregoes loss of anti-apoptotic signaling cascades in brain cells, leading to programmed cell death [35]. ONOO– can also oxidize methionine to form methionine sulfoxide, which can modulate enzyme activities. Excessive methionine sulfoxide formation correlates with development of Alzheimer’s disease in brain tissues [26]. Both IC- and EC-CuZnSODs can be inactivated by ONOO– by reacting with the active site metal and active site histidine to form a histidinyl radical, decreasing functional amounts of antioxidant systems [26]. ONOO– oxidizes and inactivates complexes of the ETC and antioxidant proteins that contribute to mitochondrial dysfunction.
PEPTIDES
Published in Stephen W. Carmichael, Susan L. Stoddard, The Adrenal Medulla 1986 - 1988, 2017
Stephen W. Carmichael, Susan L. Stoddard
Age-related changes in NPY regulation were studied in rat adrenal glands by Higuchi, Yang and Costa (1988). Neuropeptide Y immunoreactivity increased with age. Biochemical characterization showed that this increase was due to an increase in NPY and methionine sulfoxide NPY. It was suggested that age-dependent changes in NPY adrenal glands may have physiologic relevance to the regulation of catecholamine release from the adrenal medulla.
Metabolomics profiling to investigate nanomaterial toxicity in vitro and in vivo
Published in Nanotoxicology, 2020
Anne Bannuscher, Bryan Hellack, Aileen Bahl, Julie Laloy, Hildegard Herman, Miruna S. Stan, Anca Dinischiotu, Anna Giusti, Benjamin-Christoph Krause, Jutta Tentschert, Marcel Roșu, Cornel Balta, Anca Hermenean, Martin Wiemann, Andreas Luch, Andrea Haase
Met-SO is produced from methionine and reactive oxygen species (ROS) and is a well-known biomarker for oxidative stress. Elevated levels have been shown in vivo during aging and chronic smoking (Mashima, Nakanishi-Ueda and Yamamoto 2003; Stadtman et al. 2005; Suzuki et al. 2016). Met-SO was mostly increased for both precipitated SiO2 variants (SiO2_15_Unmod and SiO2_15_Amino) and TiO2 NMs in vivo and in vitro, see Figure 4 and Supplementary Figure S3. However, instilled SiO2_7 decreased the level of Met-SO, which was also detected in vitro upon CuO despite its high ability to induce ROS formation (Kitchin et al. 2017). This difference might be explained by the stronger bioactivity of SiO2_7 compared to the remaining SiO2-NMs. Also, the activity of the enzyme methionine sulfoxide reductase might be increased, which may be a consequence of oxidative stress and is a cell-protective effect (Cabreiro et al. 2006, Lai et al. 2019).
Prediction of methionine oxidation risk in monoclonal antibodies using a machine learning method
Published in mAbs, 2018
Kannan Sankar, Kam Hon Hoi, Yizhou Yin, Prasanna Ramachandran, Nisana Andersen, Amy Hilderbrand, Paul McDonald, Christoph Spiess, Qing Zhang
Oxidation of Met in proteins can result from the conversion of Met to methionine sulfoxide (MetO) by reactive oxygen species (ROS) over a broad pH range.14 Protection against Met oxidation can only be found in certain tissues and immune cells where this effect can be reversed by enzymes known as methionine sulfoxide reductases, which can reduce MetO back to Met via a thioredoxin-dependent reaction.15,16 It is believed that this reversible oxidation of Met plays a key role in the regulation of many enzymes and peptide hormones.17 Oxidized forms of proteins have been shown to exhibit decreased chemical and physical stability when compared to the unoxidized form,18,19 thereby possibly affecting their biological activity. In the case of mAbs, oxidation may interfere with the mAbs’ ability to bind to its target, especially if the oxidation occurs within the complementarity-determining region (CDR), thereby decreasing its efficacy.
Irreversible oxidative post-translational modifications in heart disease
Published in Expert Review of Proteomics, 2019
Tamara Tomin, Matthias Schittmayer, Sophie Honeder, Christoph Heininger, Ruth Birner-Gruenberger
The second sulfur containing amino acid, methionine, can also be easily oxidized by RNOS to methionine sulfoxide [52]. Although methionine sulfoxide is a chemically stable modification, methionine sulfoxide reductases are able to repair the oxidative damage [53]. Like in the case of cysteine, stronger oxidants can further push oxidation of methionine sulfoxide towards irreversible methionine sulfone formation [44].