Digestion of protein is started in the stomach where pepsinogen in the presence of HCl activates and act on proteins to form peptides. They move into the small intestine where pancreatic enzymes trypsinogen, chymotrypsinogen and procarboxypeptidases come into activation in the presence of enterokinase released by intestine converts into dipeptides. The last step involves the action of succus entericus converts dipeptides into amino acids by dipeptidases and absorbed by the wall of the small intestine and release to the bloodstream.