New Ternary Complexes of zinc ions with glycine and histidine in Solution

•The ionic composition of solutions in the zinc-histidine-glycine system has been refined.•Coordination modes of histidine in complexes of the types ZnGlymHnHism (m = 1, 2; n = 0, 1) have been revealed.•Coordination modes of amino acid residues have been proposed based on a thermodynamic approach.•The thermodynamic parameters of histidine addition to Zn(II) complexonates are analyzed.