Aluminum interaction with glutamate and α-ketoglutarate: a computational study

Aluminum, although a nonessential element in the human body, has been found to be involved in a variety of diseases. Thus, it has recently been reported that aluminum interferes with the metabolic tricarboxylic acid cycle, in which α-ketoglutarate (α-KG) is involved. α-KG is transformed to glutamate (or vice versa) by glutamate dehydrogenase (GDH). Al(III) inhibits the normal function of GDH, and it was speculated that the reason for this inhibition is triggered by the Al(III)-assisted tautomerization of α-KG from keto to enol. In the present study, we investigate the interaction of both tautomers of α-KG with Al(III) as well the complexation of glutamate to the metal. The results confirm that Al(III) indeed displaces the tautomerization reaction and favors the enol form of α-KG by 28 kcal/mol. However, when citrate is included in the system, the stabilization of the enol tautomer decreases, as this tautomer is only 1.5 kcal/mol more stable than the keto form of α-KG. Finally, possible routes for the complexation of these molecules to Al(III) in a biological environment are discussed; we propose that the ternary complexes formed by Al(III), citrate, and α-KG or glutamate can be the more likely species.