Amino acids singlet oxygen oxidation

Gracanin M., Hawkins C.L., Pattison D.J., Davies M.J. Singlet-oxygen-mediated amino acid and protein oxidation Formation of tryptophan peroxides and decomposition products. Free Radical Biology Medicine, 47 92-102 (2009). 

The rate constants for reaction of singlet oxygen vary significantly between biomolecules with greatest reactivity towards amino acid side chains, thereby affording some specificity of response [ 15]. Nevertheless, it can be considered as a powerful short-lived oxidant. The most frequent type of reaction initiated by this species is addition across unsaturated bonds yielding a cyclised product. This has been extensively reviewed by Davies [16] and will not be discussed further here. 

Table 2 Products of amino acid oxidation elicited by singlet oxygen...

Vitamin Bg is essential for more than 100 enzymes involved in protein metabolism. Pyridoxal-5 -phosphate is covalently bound to enzymes via a SchifFs base with an e-amino group of lysine in the enzyme. PLP-dependent enzymes are involved in important steps of amino acid metabolism, hemoglobin formation and chlorophyll biosynthesis. Vitamin Bg could have a role in preventing oxidative stress of the cells and is an impotent quencher of singlet oxygen. 

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