What secretions are needed to digest complex proteins into single amino acids for absorption?

Digestion of proteins into smaller units (tripeptides, dipeptides, amino acids) occurs in both, the stomach and the small intestine by the enzymes peptidases. Enzymes involved in protein digestion are:

• Pepsin-secreted from gastric chief cells of stomach; acts on low pH that is achieved with HCl in stomach

• Trypsin-secreted from pancreas; protease that cleaves proteins at the carboxyl side of the amino acids

• Chymotrypsin-secreted by the pancreas, cleaves peptide amide bonds at N-terminal

• Elastase-secreted from the pancreas

• Carboxypeptidase - secreted from the pancreas, hydrolyzes a peptide bond at the C-terminal of a protein.