Where does digestion of protein occur?

Digestion of protein starts in the stomach and does not occur in the buccal cavity (mouth). Acidic environment (low pH) due to HCL (hydrochloric acid) in the stomach allow for pepsinogen to be converted into pepsin, an enzyme which baggings digestion of big proteins into smaller peptides. Muscular nature of stomach and its contraction also facilitate mixing of food bolus with the acidic solution. After leaving the stomach and entering the duodenum, proteins undergo the next step of digestion. Pancreatic juice, which flows into the duodenum contains tripsin which further digests smaller peptide into tripeptides and dipeptides (3 and 2 amino acids respectively). Other specific enzymes such as carboxypeptidases are also secrerted in the pancreatic juice. Finally, small peptides are digested into amino acids directly on the lining of the small intestine where they are absorbed by membrane-bound enzymes.