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An esr study of radical intermediates formed by γ ‐ radiolysis of tripalmitin and dipalmitoyl phosphatidylethanolamine
Author(s) -
Sevilla C. L.,
Swarts S.,
Sevilla M.D
Publication year - 1983
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/bf02660206
Subject(s) - radical , chemistry , radiolysis , tripalmitin , electron paramagnetic resonance , photochemistry , deprotonation , phosphatidylethanolamine , ion , organic chemistry , phospholipid , nuclear magnetic resonance , chromatography , biochemistry , physics , membrane , phosphatidylcholine
Radicals resulting from the 7‐radiolysis at 77 K of neat tripalmitin and neat dipalmitoyl phosphatidylethanolamine were investigated by electron spin resonance spectroscopy (ESR). Analyses of the spectra of these complex lipids were aided by ESR studies of their components phosphorylethanolamine, palmitic acid and hexa‐decane. Concentrations of various radicals were followed as a function of temperature after γ‐irradiation at 77 K. Both tripalmitin and dipalmitoyl phosphatidylethanolamine show anion radicals formed by electron addition to the ester groups and aliphatic side‐chain radicals (‐CH 2 ‐CH‐CH 2 ‐) which are thought to be the result of deprotonation of the original positive hole. Computer analyses of the spectra as the temperature increases show loss of the anion radicals with an increase in a new radical produced by the abstrac‐tion of a hydrogen atom from the α carbon on an acyl side chain. In the case of dipalmitoyl phosphatidylethanolamine, a radical of the phosphorylethanolamine portion of the molecule is detected as an intermediate. Mechanisms for the formation and decay of the free radical intermediates are discussed.