Thiyl radical attack on polyunsaturated fatty acids: a possible route to lipid peroxidation.
Absolute rate constants have been measured for the reaction of cysteinyl free radicals, CysS., with linoleic (18:2), linolenic (18:3) and arachidonic acid (20:4) in water/alcohol mixtures using the radiation chemical technique of pulse radiolysis. They are in the order of 10(6)-10(7) M-1 s-1 and increase with the number of biallylic functions, and with the polarity of the solvent. The reaction is shown to be a hydrogen atom abstraction from biallylic C-H bonds and yields pentadienyl radicals. The thiol mediated repair of the latter is considerably slower. Thiyl free radicals must consequently be considered as a potential source of lipid peroxidation.
Schöneich
C
C
Hahn-Meitner-Institute Berlin, FRG.
Asmus
K D
KD
Dillinger
U
U
von Bruchhausen
F
F
D001667:Binding, Competitive; D003545:Cysteine; D005231:Fatty Acids, Unsaturated / Q000378:metabolism*; D005609:Free Radicals; D006207:Half-Life; D007700:Kinetics; D008042:Linolenic Acids; D015227:Lipid Peroxidation; D011675:Pulse Radiolysis; D012997:Solvents; D013329:Structure-Activity Relationship; D017962:alpha-Linolenic Acid
D005231:Fatty Acids, Unsaturated; D005609:Free Radicals; D008042:Linolenic Acids; D012997:Solvents; D017962:alpha-Linolenic Acid; D003545:Cysteine