Prediction of antimicrobial activity of a food peptide and evaluation of its effectiveness in vitro

Food antimicrobial peptides are increasingly relevant in the treatment of bacterial infections and have a number of advantages in comparison with drugs: slower emergence of resistance in bacterial strains, high activity against antibiotic films and immunomodulatory properties. The physico-chemical properties causing antimicrobial properties include: cationic charge, hydrophobicity, molecular weight and amino acid sequence. Promising sources of antimicrobial peptides are milk proteins, in particular, cow colostrum proteins. The aim of the work is to extract a peptide from the pepsin hydrolysate of cow colostrum, predict its antimicrobial activity using a bioinformatic approach and confirm its effectiveness in vitro. The molecular mass distribution of the peptide was evaluated by mass spectrometric method. The analysis of mass spectra was carried out using the Mascot program, the Peptide Fingerprint option – using the Protein NCBI database. Microsequencing was performed using a MiSeq sequencer. Modeling of the spatial structure of the isolated peptide was carried out using the Schrodinger Maestro molecular modeling program. The antimicrobial activity of the peptide was studied by the disco-diffusion method on gram-positive and gram-negative bacteria. The peptide has been isolated from the pepsin hydrolysate of cow colostrum, which is absent in the known proteomic bases Protein NCBI and AVPdb and, accordingly, its biological activity and functions have not been studied. The resulting peptide belongs to linear alpha-helical peptides consists of 11 amino acid sequences ANRKLRANKSR with a molecular weight of 8.2 kDa, an isoelectric point at 12.79, a charge of +5 (cationic), hydrophilicity (hydrophobicity) +20.84 Kcal*mol-1. As a result of in vitro studies, it was found that the isolated peptide has antimicrobial activity against E. coli ATCC 25922 and B. subtilis and antimicrobial action against C. albicans.