Methionine with peroxidizing lipid

Some amino acids may be oxidized by reacting with free radicals formed by lipid oxidation. Methionine can react with a lipid peroxide to yield methionine sulfoxide. Cysteine can be decomposed by a lipid free radical according to the following scheme ... 

In addition to cytochrome P-450 induction, other diet induced metabolic effects are likely to be involved in carcinogenesis. High temperature processing or long-term storage of foods with attendant exposure to oxygen can lead to the formation of lipid peroxides and oxidized sulfur amino acids in the food. The partially oxidized S-amino acids cystine monoxide (CMO) and methionine sulfoxide (MSO) are nutritionally available, but require in vivo conversion to the reduced amino acids at the... 

Peroxynitrite is a nonspecific oxidant that reacts with all classes of biomolecules depleting low-molecular-weight antioxidants, initiating lipid peroxidation, damaging nucleic acids and proteins. Its reactions are much slower than those of the hydroxyl radical but are faster than those of hydrogen peroxide. Comparison of peroxynitrite reactivity with various amino acid residues of human serum albumin have shown that cysteine, methionine, and tryptophan are the most reactive... 

S-Adenosyl-L-methionine (50 mg/kg given i.p.ever day for 3 days 1 h before ischaemia/reper-fusion) in a combined model of permanent focal ischaemia and global reperfusion in the rat brain reduced the production of thiobarbituric acid-reactive substances after induction with ferrous salt as an indicator of brain lipid peroxidation (Villalobos et al. 2000). Total glutathione production was increased. These changes were accompanied by an increase in mitochondrial capacity to reduce tet-raphenyl tetrazolium. 

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