Protein Digestion Mechanism
begins in stomach. It continues in small intestines till the end product of the protein digestion amino acid is absorbed by the blood.
Protein digestion is accomplished by
protein digesting enzymes
Proteins are very complex molecules with complex chains of amino acids. The first step in digestion of proteins is to break down these complex molecules by breaking the chain.
Digestion of proteins in the stomach:
In stomach the proteins are first attacked by
Hydrochloric acid is stomach’s gastric acid. It breaks down the simple protein molecules directly to amino acids.
Enzymes play major role in protein digestion. The gastric enzyme pepsin is the first enzyme to act upon the food in stomach. This enzyme mixes with hydrochloric acid and aids the process of digestion of protein. Protease is the enzyme that breaks down collagen, the fibrous protein of animal connective tissue, into amino acids.
Several factors influence the action of the above explained enzymes in the process of protein digestion. Here are a few of them:
- Amount of protein food
- Concentration of the enzyme
- Temperature of the ingested food
- Time of taking the food
- Acidity of the food
- Presence of any inhibitors of digestion such as antacids.
Protein digestion in small intestines:
Digestive enzymes known as
are responsible for the digestion of proteins in small intestines. Trypsin breaks down a protein into simple and single amino acid by the process known as hydrolysis.
Hydrolysis is the process of breaking two amino acids by inserting a water molecule between the bond.
This broken down amino acids pass through intestinal lining into tiny capillaries. From these capillaries these amino acids go into villi which are the finger like projections on the wall of small intestines. The blood stream distributes these amino acids to the cells and tissues of the body which aid in the repair of cell structures.
The undigested part of the food is passed on to the large intestine for further absorption and elimination.