Open AccessAmino Acid Sequence of Chicken Cu, Zn‐Containing Superoxide Dismutase and Identification of Glutathionyl Adducts at Exposed Cysteine Residues
Author(s) -
Schininà M. Eugenia,
Carlini Patrizia,
Polticelli Fabio,
Zappacosta Francesca,
Bossa Francesco,
Calabrese Lilia
Publication year - 1996
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1996.0433k.x
Subject(s) - superoxide dismutase , chemistry , cysteine , amino acid , molecular mass , biochemistry , dismutase , peptide sequence , protein subunit , glutathione , superoxide , enzyme , gene
The copper, zinc‐containing superoxide dismutase electromorphs from chicken erythrocytes have been isolated, their complete amino acid sequence determined and the identity of the protein moieties established. All electromorphs are constituted by a polypeptide chain made of 153 amino acid residues, corresponding to a molecular mass of 15598 Da. Accurate molecular mass determination by electrospray mass spectrometry of the separated electromorphs unequivocally proved that, in the chicken superoxide dismutase, either one or two cysteine residues/subunit are involved in a mixed disulfide with glutathione. The same post‐translational modification has been proven to occur in human superoxide dismutase. A different rate of S‐thiolation by endogenous glutathione was also demonstrated to be responsible for charge heterogeneity in cells. Effect of this modification on the catalytic and molecular properties of superoxide dismutases, and possible mechanisms for the S‐thiolation process, were also investigated and discussed.