TY - JOUR
T1 - Bovine erythrocyte superoxide dismutase. Subunit structure and sequence location of the intrasubunit disulfide bond
AU - Abernethy, J. L.
AU - Steinman, H. M.
AU - Hill, R. L.
N1 - Copyright:
Copyright 2004 Elsevier B.V., All rights reserved.
PY - 1974
Y1 - 1974
N2 - The subunit assembly of bovine erythrocyte superoxide dismutase was studied through analysis of the effects of heat, removal of metal ion cofactors and disulfide bond reduction, upon the dissociation of the subunits. Investigations utilizing sodium dodecyl sulfate acrylamide gel electrophoresis and sedimentation equilibrium analysis demonstrated that the 2 polypeptide subunits of the protein are not covalently joined, but are associated through unusually strong noncovalent interactions. This absence of intersubunit disulfide bonds, in conjunction with the titration of a single free sulfhydryl group per subunit polypeptide chain, necessitates that the 3 half cystine residues per subunit exist as 1 residue of cystine, forming an intrasubunit disulfide bond, and 1 residue of cysteine. The specific half cystine residues participating in the disulfide linkage and contributing the free thiol function were identified. Analysis of the products of cyanogen bromide cleavage, with acrylamide gel electrophoresis, demonstrated that the intrasubunit disulfide links 1 half cystine residue in the sequence NH2 terminal to Met 115, to another half cystine residue in the sequence COOH terminal to Met 115. Though conventional procedures of enzymatic digestion, peptide isolation and peptide characterization, Cys 55 and Cys 144 are shown to participate in the intrasubunit disulfide linkage, and Cys 6 to exist as free cysteine. (48 references).
AB - The subunit assembly of bovine erythrocyte superoxide dismutase was studied through analysis of the effects of heat, removal of metal ion cofactors and disulfide bond reduction, upon the dissociation of the subunits. Investigations utilizing sodium dodecyl sulfate acrylamide gel electrophoresis and sedimentation equilibrium analysis demonstrated that the 2 polypeptide subunits of the protein are not covalently joined, but are associated through unusually strong noncovalent interactions. This absence of intersubunit disulfide bonds, in conjunction with the titration of a single free sulfhydryl group per subunit polypeptide chain, necessitates that the 3 half cystine residues per subunit exist as 1 residue of cystine, forming an intrasubunit disulfide bond, and 1 residue of cysteine. The specific half cystine residues participating in the disulfide linkage and contributing the free thiol function were identified. Analysis of the products of cyanogen bromide cleavage, with acrylamide gel electrophoresis, demonstrated that the intrasubunit disulfide links 1 half cystine residue in the sequence NH2 terminal to Met 115, to another half cystine residue in the sequence COOH terminal to Met 115. Though conventional procedures of enzymatic digestion, peptide isolation and peptide characterization, Cys 55 and Cys 144 are shown to participate in the intrasubunit disulfide linkage, and Cys 6 to exist as free cysteine. (48 references).
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M3 - Article
C2 - 4436313
AN - SCOPUS:0016270016
SN - 0021-9258
VL - 249
SP - 7339
EP - 7347
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 22
ER -