We studied the interaction of several metal ions with the copper chaperone fromEnterococcus hirae(EhCopZ). We show that the stoichiometry of the protein–metal complex varies with the experimental conditions used. At high con-centration of the protein in a noncoordinatingbuffer, a dimer, (EhCopZ)2–metal, was formed. The presence of a potentially coordinatingmolecule L in the solution leads to the formation of a monomeric ternary complex, EhCopZ– Cu–L, where L can be a buffer or a coordinatingmole-cule (glutathione, tris(2-carboxyethyl)phosphine). .
