Electronic structure calculation study of metal complexes with a phytosiderophore mugineic acid

Structural and thermodynamic properties of biologically important metal-mugineic acid complexes have been studied from the theoretical side in order to understand the metal-chelating mechanism of phytosiderophore mugineic acid at an atomic level. Density-functional theory methods combined with the polarizable continuum model (PCM) have been employed to obtain free energies of complex formation and redox potentials for metal-mugineic acid complexes in solution. It has been found that the free energies of complex formation calculated at the B3LYP/PCM level of theory are in moderate agreement with available experimental results. The inclusion of explicit water molecules interacting with the carboxylic groups in deprotonated mugineic acid through strong hydrogen-bonds is found to further improve the calculated free energies of complex formation. (C) 2011 Elsevier B.V. All rights reserved.