Pepsin B

Pepsin B is a type of protease enzyme that is involved in the digestion of proteins in the stomach. It is one of the several types of pepsin enzymes, which are produced by the chief cells in the gastric glands of the stomach lining. Pepsin B is less well-known compared to pepsin A, but it plays a significant role in the breakdown of proteins into smaller peptides.

Structure and Function

Pepsin B, like other pepsins, is synthesized as an inactive precursor called pepsinogen. When pepsinogen is secreted into the stomach, it is activated by the acidic environment (pH 1.5 to 2) to form active pepsin B. The enzyme cleaves peptide bonds, particularly those involving aromatic amino acids such as phenylalanine, tyrosine, and tryptophan.

Production and Secretion

Pepsin B is produced by the chief cells located in the gastric glands of the stomach. The secretion of pepsinogen, the precursor to pepsin B, is stimulated by the presence of food in the stomach and by the hormone gastrin. Once secreted, pepsinogen is converted to pepsin B in the acidic environment of the stomach.

Role in Digestion

Pepsin B contributes to the initial stages of protein digestion by breaking down large protein molecules into smaller peptides. This process is crucial for the subsequent action of other proteases in the small intestine, such as trypsin and chymotrypsin, which further degrade peptides into amino acids that can be absorbed by the body.

Clinical Significance

Abnormalities in the production or activity of pepsin B can lead to digestive disorders. For instance, insufficient pepsin B activity can result in incomplete protein digestion, leading to symptoms such as bloating and malnutrition. Conversely, excessive pepsin activity can contribute to conditions like peptic ulcers and gastritis.

Related Enzymes

• Pepsin A
• Pepsin C
• Gastric lipase
• Rennin

See Also

• Protease
• Gastric glands
• Chief cells
• Digestion
• Peptic ulcer
• Gastritis