Question

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Name the five enzymes involved in protein digestion, and list the site of action for each of the enzymes.

Answer 1

Answer: Protein digestion occur by hydrolysis of peptide bond that binds amino acids in a polypeptide chain. Five enzymes that are involved in protein digestion are:

(1) Pepsin: Presence of food in stomach causes G cell of mucosa to produce gastrin hormone which in turn stimulates pareital cells of gastric glands to secrete hydrochloric acid. Gastric glands also produced mucus and pepsinogen which at low pH is converted into pepsin.The site of action of pepsin is stomach.

(2) Trypsin:Once the gastric content enters duodenum and jejunum,hormone cholecystokinin causes exocrine pancrease to release enzyme rich juice. Trypsinogen is inactive proenzyme activated into trypsin.Trypsin is protein-digesting enzyme present in pancreatic juices secreted into small intestine.

(3) Chemotrypsin: This is also present in pancreatic juice which helps in protein digestion.Its site of action is duodenum.

(4) Elastase: This protein digesting enzymes is also present in pancreatic juice. It is activated by trypsin in duodenum.

(5) Carboxypeptidase: It is produced in inactive form as procarboxypeptidase which is activated into active form by trypsin.Its site of action is duodenum and jejunum.