Investigation on the micro-mechanisms of Al(3+) interfering the reactivities of aspartic acid and its biological processes with Mg(2+).

Density functional theory (DFT) has been applied to study the micro-mechanisms of Al3+ interfering the reactivities of aspartic acid (H2asp) and its biological processes with Mg2+. All the 46 stable conformers of Hasp- and 3 of asp2- have been determined at the B3LYP/6-311++G** level, showing that the 7 most stable conformers of Hasp- all present a very strong and linear O-H...O H-bond between carboxyl and carboxylic acid groups with the bond energy high up to 162 kJ mol(-1). The reaction thermodynamics and micro-mechanism between Al3+ and Hasp- (or asp2-) in aqueous phase have been investigated by the combined application of supramolecular model and polarizable continuum IEFPCM solvent model, firstly revealing Al3+ interfering in the biological processes of aspartic acid. The substitution thermodynamics and mechanisms of Mg2+ by Al3+ in the biological processes between the species of aspartic acid and Mg2+ in aqueous phase were probed, revealing the facile displacement of Mg2+ by Al3+. These results may provide a reasonable mechanism of Al3+ biological toxicity at the microscopic level.