The exchange of histidine C-2 protons in superoxide dismutases. A novel method for assigning histidine-metal ligands in proteins.
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ABSTRACT: The rates of exchange of the C-2 protons of histidine residues in copper-zinc superoxide dismutase are substantially decreased by metal ion binding. This observation was used to distinguish between ligand and non ligand histidine residues in bovine and yeast copper-zinc superoxide dismutases; the effect was shown to depend only on metal ion co-ordination and not as a consequence of concomitant changes in protein structure. Selective deuteration of the zinc-only proteins at pH (uncorrected pH-meter reading) 8.2 and 50 degrees C resulted in the distinction between copper and zinc ligand resonances in the 1H n.m.r. spectrum of the enzymes. This method is proposed as a generally applicable technique for identifying histidine residues as ligands in metalloproteins.
SUBMITTER: Cass AE
PROVIDER: S-EPMC1161480 | biostudies-other | 1979 Oct
REPOSITORIES: biostudies-other
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