Speciation and structural aspects of interactions of Al(III) with small biomolecules

Complexes formed with low molecular mass biomolecules are the ‘dynamic or mobile units’ of Al(III), which may be involved in the absorption and transport processes of this toxic element in organisms. This paper reviews the interactions of Al(III), from speciation and structural aspects, with biologically relevant endogenous and exogenous small biomolecules such as inorganic ligands (hydroxide, fluoride, (oligo)phosphates and silicic acid), amino acids, phosphorylated amino acids, oligopeptides, biophosphates including nucleotides, phosphonates, hydroxamates, and aromatic and aliphatic hydroxycarboxylates. The importance of time in biospeciation is demonstrated on the examples of binary and ternary systems involving Al(III) and citric acid. Examples are also given for the implications of the speciation of Al(III) with such small biomolecules in biology.