Insights Into the Inhibitory Effect of Ofloxacin on Pepsin Through Peptidomics and Bioinformatics Approaches

The hydrolysis of proteins by pepsin is of great significance for the biological utilization of proteins and the discovery of functional peptide molecules. Bovine serum albumin (BSA) and bovine collagen I (BCI) are both commonly used natural source proteins for studying the hydrolysis characteristics of pepsin. UHPLC − MS/MS, peptidomics, and molecular docking technologies were employed to investigate the underlying mechanism responsible for the inhibitory effect of ofloxacin on pepsin. The molecular weight distribution of peptides produced by pepsin in this study was mostly in the range of 600 Da to 1800 Da, and peptide segments were mostly composed of 9−11 amino acids. The predominant terminal amino acids were proline, glycine, leucine, valine, serine, and threonine. Ofloxacin led to conformational changes of the hydrolysis active sites of pepsin by forming hydrogen bonds with aspartic acids. When the key aspartic acid residues in the active center of pepsin were inhibited, the numbers of peptides TPAQD, VSVDAA, TVLFD, and TVIFD were upregulated. The hydrolysis characteristics of pepsin were changed, shown as an increase in the proportion of low molecular weight peptides and a decrease in the hydrophobicity of peptide segments in the hydrolysates. The study contributed to the evaluation of the activity of peptides from homologous protein hydrolysis by pepsin and the elucidation of the inhibitory mechanism of ofloxacin on pepsin.