Oxidation is involved not only in t

Oxidation is involved not only in the formation of
AGEs but also in protein aging, where proteins are directly
altered by reactive oxygen species (e.g., peptidebound
cleavage, nitration, chloration) to generate advanced
oxidation protein products (AOPPs) (1, 7 ).
The terminology “AOPPs” was initially applied to
products formed upon protein oxidation and grouped
on the basis ofcommonspectrophotometric characteristics
without definition of any specific structural
criteria. The major studied AOPPs are methionine
sulfoxide (formed by methionine oxidation) and
3-nitrotyrosine (formed by tyrosine nitration) (8 ).