Proteins are large molecules that are needed by the body but cannot be absorbed directly.
The protein needs to be broken down into amino acids then those amino acids recombined to form specialized proteins such as enzymes, antibodies and hormone. The breakdown of protein occurs from the stomach and continue to the small intestine. Pepsin initiate the breakdown of protein by breaking peptide bonds holding protein together. It is an active protein digesting enzyme of the stomach. Proteins are then broken down into polypeptide in the stomach which then move to the small intestine.
Enzymes such as the trypsin, chymotrypsin and carboxypeptidase are secreted from the pancreas and enters the duodenum with the help of brush border enzymes. The peptide bonds holding the polypeptide are broken down into small peptides (two or more amino acids). The enzymes continue to break down molecules into amino acid which are very small and are then absorbed through the small intestine lining and into the blood stream.