The oxidation produced by hydrogen peroxide on Ca-ATP-G-actin

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 H2O2 on actin is the oxidation of Cys374, we have found that Met44, Met47, Met176, Met190, Met269, a...

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Bibliographic Details
Published in:Protein science 2000-09, Vol.9 (9), p.1774-1782
Main Authors: MILZANI, ALDO, ROSSI, RANIERI, DI SIMPLICIO, PAOLO, GIUSTARINI, DANIELA, COLOMBO, ROBERTO, DALLEDONNE, ISABELLA
Format: Article
Language:English
Subjects:
actin oxidation
Actins - chemistry
Adenosine Triphosphate - chemistry
Amino Acid Sequence
Animals
conformational changes
cyanogen bromide
cysteine
Hydrogen Peroxide - chemistry
methionine
Methionine - chemistry
Models, Molecular
Molecular Sequence Data
Oxidation-Reduction
Protein Conformation
Rabbits
surface hydrophobicity
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Summary: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 H2O2 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.
ISSN:0961-8368
1469-896X
DOI:10.1110/ps.9.9.1774