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The oxidation produced by hydrogen peroxide on Ca‐ATP‐G‐actin
Author(s) -
Milzani Aldo,
Rossi Ranieri,
Simplicio Paolo Di,
Giustarini Daniela,
Colombo Roberto,
Dalledonne Isabella
Publication year - 2000
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.9.9.1774
Subject(s) - methionine sulfoxide , hydrogen peroxide , chemistry , methionine , actin , proteolysis , monomer , tryptophan , polymerization , actin binding protein , protein filament , oxidative phosphorylation , biochemistry , biophysics , amino acid , enzyme , cytoskeleton , actin cytoskeleton , organic chemistry , biology , polymer , cell
We report here that in vitro exposure of monomeric actin to hydrogen peroxide leads to a conversion of 6 of the 16 methionine residues to methionine sulfoxide residues. Although the initial effect of H 2 O 2 on actin is the oxidation of Cys374, we have found that Met44, Met47, Met176, Met190, Met269, and Met355 are the other sites of the oxidative modification. Met44 and Met47 are the methionyl sites first oxidized. The methionine residues that are oxidized are not simply related to their accessibility to the external medium and are found in all four subdomains of actin. The conformations of subdomain 1, a region critical for the functional binding of different actin‐binding proteins, and subdomain 2, which plays important roles in the polymerization process and stabilization of the actin filament, are changed upon oxidation. The conformational changes are deduced from the increased exposure of hydrophobic residues, which correlates with methionine sulfoxide formation, from the perturbations in tryptophan fluorescence, and from the decreased susceptibility to limited proteolysis of oxidized actin.