The high acidity denatures those proteins, and the pepsi breaks those proteins down into smaller polypeptides. Now, those polypeptides travel into the lumen of our small intestine. And in the lumen, these three proteolytic enzymes cleave the polypeptides into small peptides. And then those small peptides interact with the enzymes, the proteolytic digestive enzymes of the brush border of this microvilli, as shown here, and they break them down into tripeptides, dipeptides and amino acids. Dipeptide simply means we have a single peptide bond. So we have two amino acids in the peptide.