Theoretical–experimental prediction of the selectivity between polyamidoamine dendrimers and bioactive peptides derived from amaranth seeds

Abstract

Seed proteins, especially those of amaranth, are characterized using different peptides with important biological functions. The aim of this work is to describe, at a theoretical–experimental level, the selective separation of encrypted peptides with high-added value. The interactions between amino acid–PAMAM and peptide–PAMAM were determined using quantum chemistry and instrumental techniques of structural analysis, with the obtained results showing correlation between both methods of identification and characterization. The molecular properties of amino acids, peptides (models) and PAMAM were determined using density functional theory (DFT), specifically B3LYP and the 6-31G(d,p) basis set. The synthesis of the dendrimer (PAMAM) was carried out by optimizing the traditional process to reduce cost and waste generation. The analysis of the vibrational frequencies between tyrosine and PAMAM using the DFT method correlated satisfactorily with the experimental data. The interaction energy of the most stable complexes was between those of the first generation PAMAM dendrimer, the amino acid tyrosine and the PAMAMAM–YLAGKPQQEH peptide, with a value of −31.25 kcal mol⁻¹ and −27.19 kcal mol⁻¹, respectively. Likewise, the molecular electrostatic potential map and the intermolecular hydrogen bonds allowed visualizing the interactions between the captured atoms (amino acids and peptides) and the synthesized PAMAM. This work showed evidence at the molecular level of selectivity of encrypted oligopeptides. The theoretical study was determined to define the types of peptides that could interact with PAMAM after enzymatic hydrolysis, as well as the type of interaction, and the atoms involved in the formation of a dendrimer–peptide complex. Subsequently, at the experimental level, these residues were mapped by mass spectrometry in a MALDI-TOF detector, having results that can be homologated with the theoretical results. This study opens the door to novel studies for the separation of bioactive peptides.