Thermodynamic and spectroscopic studies have shown that the insertion of α-hydroxylmethylserine (HmS) residues into the N-terminal peptide motif of human serum albumin results in a very powerful chelating agent for Cu²⁺ and Ni²⁺ ions. The insertion of two HmS residues results in the HmS–HmS–His–OH/NH₂ sequence, which is the most effective chelating agent based on an albumin-like sequence for both studied metal ions, especially when the C-terminal carboxylate is protected by an amide function.