INVESTIGADORES
GOMEZ-MEJIBA sandra Esther
artículos
Título:
CU,ZN-SUPEROXIDE DISMUTASE-DRIVEN FREE RADICAL MODIFICATIONS:COPPER AND CARBONATE RADICAL ANION-INITIATED PROTEIN RADICAL CHEMISTRY
Autor/es:
SANDRA E GOMEZ-MEJIBA; RAMIREZ DC; CORBETT, JT; DETERDING, LJ; TOMER, KB; MASON, RP
Revista:
BIOCHEMICAL JOURNAL
Editorial:
PORTLAND PRESS LTD
Referencias:
Lugar: Londres; Año: 2009 p. 341 - 353
ISSN:
0264-6021
Resumen:
The understanding of the mechanism, oxidant(s) involved and how and what
protein radicals are produced during the reaction of wild-type SOD1
(Cu,Zn-superoxide dismutase) with H2O2 and their fate is incomplete, but
a better understanding of the role of this reaction is needed. We have
used immuno-spin trapping and MS analysis to study the protein
oxidations driven by human (h) and bovine (b) SOD1 when reacting with
H2O2 using HSA (human serum albumin) and mBH (mouse brain homogenate) as
target models. In order to gain mechanistic information about this
reaction, we considered both copper- and CO3(*-) (carbonate radical
anion)-initiated protein oxidation. We chose experimental conditions
that clearly separated SOD1-driven oxidation via CO(*-) from that
initiated by copper released from the SOD1 active site. In the absence
of (bi)carbonate, site-specific radical-mediated fragmentation is
produced by SOD1 active-site copper. In the presence of (bi)carbonate
and DTPA (diethylenetriaminepenta-acetic acid) (to suppress copper
chemistry), CO(*-) produced distinct radical sites in both SOD1 and HSA,
which caused protein aggregation without causing protein fragmentation.
The CO(*-) produced by the reaction of hSOD1 with H2O2 also produced
distinctive DMPO (5,5-dimethylpyrroline-N-oxide) nitrone adduct-positive
protein bands in the mBH. Finally, we propose a biochemical mechanism
to explain CO(*-) production from CO2, enhanced protein radical
formation and protection by (bi)carbonate against H2O2-induced
fragmentation of the SOD1 active site. Our present study is important
for establishing experimental conditions for studying the molecular
mechanism and targets of oxidation during the reverse reaction of SOD1
with H2O2; these results are the first step in analysing the critical
targets of SOD1-driven oxidation during pathological processes such as
neuroinflammation.