AN INVESTIGATION OF SUPEROXIDE-DISMUTASE LYS-143, ILE-143, AND GLU-143 MUTANTS - CU2CO2SOD DERIVATIVES

The Cu//2Co//2 derivatives of recombinant human superoxide dismutase from yeast in which Arg-143 has been substituted with Ile, Lys, and Glu residues have been prepared and characterized through electronic spectroscopy. The **1H NMR spectra have been measured and compared with those of the wild type derivative. The structure of the four derivatives appears very similar. The same holds for the four azide derivatives in which a histidine, possibly His-46, is replaced by the anion. On the other hand the affinity of N//3** minus for the proteins is 154, 63, 16, and 6 M** minus **1 for wild type, Lys-143, Ile-143, and Glu-143 derivatives, respectively. Despite the similarity of the chromophores, the affinity of anions is shown to be controlled by the charge at the 143 position.