Production of Collagen-Derived Hydroxyproline (Hyp)-Containing Di- and Tripeptides by Brush Border Membrane Enzymes and Their Absorption Characteristics

Abstract

Our previous study demonstrated oral ingestion of collagen hydrolysate facilitated absorption of hydroxyproline (Hyp)-containing di- and tripeptides in micromolar range. To elucidate how the peptides were generated and absorbed, simulated digestion with brush border membrane (BBM) enzymes and Caco-2 model were used. Results showed Xaa-Hyp (XOs), Xaa-Hyp-Gly (XOGs), and Gly-Pro-Hyp (GPO) were produced by BBM enzymes, with aminopeptidaseN, carboxypeptidases, and DPP-IV playing crucial roles. Differential contents of precursor peptides containing 3/4 amino acid residues in CTH (low-molecular-weight collagen hydrolysate) and CH (high-molecular-weight collagen hydrolysate) caused discrepancies in production rates of XOs and XOGs. Hyp-containing di- and tripeptides could be transported intact across cell monolayer, with the highest apparent permeability coefficient (Papp, (23.91 ± 3.18) × 10-8 cm/s) observed for GPO. Molecular docking revealed a positive correlation between Papp values and affinity to PepT1 of XOs, providing a strategy to partially predict permeability of peptides resistant to peptidase hydrolysis.

Keywords: collagen hydrolysate, Hyp-containing dipeptide, Hyp-containing tripeptide, brush border membrane, Digestion, Caco-2