ALUMINUM(III) INTERACTIONS WITH THE ACIDIC AMINO-ACID CHAINS

We have performed an ab initio study of aluminum(III) cation with the aspartic and glutamic amino acid residues, i.e., the carboxylate group . Density functional theory methodology was used, and the covalent and noncovalent interactions were analyzed using natural bond orbital the ory. First we have investigated the smallest functional moiety of thes e amino acids, the carboxylate anion. Additionally, we have sequential ly introduced two methyl groups to more accurately represent the aspar tic and glutamic acid chains. We have compared these data with the non toxic metal cation, e.g., magnesium(II). Our calculations demonstrate that aluminum(III) binds much more tightly to the ligands than magnesi um(II) and the addition of the methyl groups leads to stronger bonds, though the effect of the second methyl group is less than that of the first.