Mixed Ligand Zinc Complexation with Ornithine and Histidine in Aqueous Solution

The formation of mixed-ligand complexes of various compositions in the Zn-L-histidine (His)-L-ornithine (Orn) system has been studied by pH-metry, calorimetry, and NMR spectroscopy. The thermodynamic parameters (log K, Delta(r)G(0) Delta H-r, Delta S-r) of the reactions of their formation at 298.15 K and ionic strength I = 0.5 (KNO3) have been calculated. Based on the comparative analysis of thermodynamic parameters, the most probable method for the coordination of amino acid residues in mixed complexes has been proposed.

Automated summary

The formation of different compositions of mixed-ligand complexes in the Zn-L-histidine-L-ornithine system has been studied using pH-metry, calorimetry, and NMR spectroscopy. Thermodynamic parameters have been calculated and compared to propose the most probable method for the coordination of amino acid residues in mixed complexes.