The Role of Histidine in a Copper-Specific Metallothionein

Metallothioneins achieve metal binding specificity by modulation of their amino acid sequences through evolution. Non-coordinating residues seem to play a key role in this function, and among them histidine may be of particular importance. Here we report how this residue regulates CuI binding to a highly copper specific isoform, the CuMT of the snail Helix pomatia, by analysis of the recombinant complexes yielded by a constructed mutant where this residue has been changed to an alanine.