Primary structure of porcine Cu,Zn superoxide dismutase

The complete amino acid sequence of Cu,Zn superoxide dismutase from porcine erythrocytes has been determined. Comparison of the sequence with that of the bovine enzyme shows an overall high degree of homology with conservation of the crucial residues and the presence of two regions prone to variation. In one of these hypervariable regions the insertion of one residue with respect to the bovine enzyme and evidence of structural microheterogeneity has been observed. On the basis of the three-dimensional structure of the bovine enzyme no obvious relationship is apparent between a specific amino acid replacement and the unique pH-dependence pattern of the activity of the porcine enzyme.