title: Repair of amino acid radicals by a vitamin E analogue.
abstract: Free radicals derived from one-electron oxidation of the amino acids tryptophan, tyrosine, methionine and histidine have been found to be rapidly (k = 10(7) -10(9) dm3 mol-1 s-1) and efficiently repaired by Trolox C, a vitamin E analogue. The reactions form a relatively stable phenoxyl radical of Trolox C (lambda max = 440 nm; epsilon = 5.4 X 10(3) mol dm-3 cm-1). The radical cation of tryptophan is more rapidly repaired than the neutral tryptophan radical. Repair of tryptophanyl radicals in the enzyme lysozyme has also been observed. The results suggest that a function of alpha-tocopherol in membranes may be the repair of radicals of integral membrane proteins.
mesh_terms: D000596:Amino Acids; D000975:Antioxidants; D001578:Benzopyrans; D002839:Chromans; D005609:Free Radicals; D006639:Histidine; D008715:Methionine; D009113:Muramidase; D010084:Oxidation-Reduction; D011675:Pulse Radiolysis; D014364:Tryptophan; D014443:Tyrosine
chemical_list: D000596:Amino Acids; D000975:Antioxidants; D001578:Benzopyrans; D002839:Chromans; D005609:Free Radicals; D014443:Tyrosine; D006639:Histidine; D014364:Tryptophan; D008715:Methionine; D009113:Muramidase; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid