Zn (II) chelating with L-alanine: Identification of the binding sites in complexes and their zwitterionic forms

MEDINA AV; LEDESMA A E

Congreso; L Reunión Anual SAB; 2022

Zinc is considered as one of the most important trace elements in the human body, and itscoordination chemistry is of considerable interest. Zn is present in metalloproteins and hasstructural, functional and regulatory contributions of the normal development of immune functions in humans and animals. Zn2+ can create inert chelate complexes by accepting the free electron pairs of O-, N-, S- from certain amino acid motifs. Interaction between transition metals and amino acids are very interesting in the biological applications, metal complexes of transition metal ions can be used as models to study the pharmocodynamic effects of drugs.In this work we used methods of theoretical chemistry to investigate the conformations and energetics of the covalent, zwitterion and dipeptide complexes formed by transition metal cations Zn2+ with L-alanine, in gas phase and aqueous solution. Some properties such as HOMO-LUMO energies and binding energy were obtained by using the gradient corrected density functional theory (DFT) method with the B3LYP functional and LANL2DZ and 6-311G٭٭ basis sets. The Gaussian 16 program was employed to perform geometrical optimization of all compounds used in this work.The analysis of the molecular and supramolecular architectures showed that the LANL2DZ basis set reproduce the bests results. Theoretical geometries of Zn-L alanine were studied by quantum chemistry calculations and molecular modeling method, which provided valuable insights into the binding structures of the complexes. The amino and carboxy groups are the center of interaction with metal, being more stable the complex where the oxygen atoms are involved. The results evidenced a very high stabilization of the dipeptide complex, by two L-alanine molecules. We concluded that the carboxyl group and amino groups in the peptide have strong bonding abilities with Zn2+.