🔅 PEPSINOGEN

– Pepsinogen is a protein that is produced by the gastric chief cells in the stomach lining. It is the inactive precursor of pepsin, which is a digestive enzyme that breaks down proteins into smaller peptides in the stomach.

– Pepsinogen has an important function in the digestion of proteins, as it is activated by the acidic environment of the stomach to become pepsin. The activation mechanism of pepsinogen involves the cleavage of a 44-amino acid segment called the activation peptide from the N-terminal end of the protein. This exposes the active site of the enzyme, which contains two aspartic acid residues that are essential for the catalytic activity of pepsin. The cleavage of the activation peptide is triggered by the low pH of the gastric juice, which is mainly composed of hydrochloric acid secreted by the parietal cells in the stomach lining. The hydrochloric acid also helps to stabilize the structure of pepsin, which is optimal at pH 1.5 to 2.

– The storage of pepsinogen is mainly in the secretory granules of the gastric chief cells, where it is synthesized and transported from the endoplasmic reticulum and the Golgi apparatus. The release of pepsinogen from the gastric chief cells is stimulated by several factors, such as the hormone gastrin, the vagus nerve, and the presence of food in the stomach. The released pepsinogen is then mixed with the gastric juice and converted into pepsin.

– As a precursor to pepsin, pepsinogen plays a vital role in the digestion of proteins, as it allows the regulation of the enzyme activity and prevents the self-digestion of the stomach lining. Pepsinogen is only activated when it reaches the stomach, where it encounters the acidic pH and the presence of pepsin molecules that can act as autocatalysts. Pepsin then hydrolyzes the peptide bonds of the proteins, producing smaller peptides that can be further digested by other enzymes in the small intestine.

#FAQ

How is pepsinogen related to stomach ulcers?

– Pepsinogen being a protein produced by the gastric chief cells in the stomach lining is the inactive precursor of pepsin, which is a digestive enzyme that breaks down proteins into smaller peptides in the stomach. Pepsinogen has an important function in the digestion of proteins, as it is activated by the acidic environment of the stomach to become pepsin.

– Pepsinogen is related to stomach ulcers, which are open sores that develop on the inside lining of the stomach or the upper portion of the small intestine (duodenum). Stomach ulcers are also called gastric ulcers, and they are a type of peptic ulcer. Peptic ulcers are named for pepsin, one of the digestive juices that are found in the stomach and that sometimes leak into the duodenum. These juices are a contributing factor in peptic ulcer disease.

– The most common causes of stomach ulcers are infection with the bacterium Helicobacter pylori (H. pylori) and long-term use of nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and naproxen. These factors can damage the protective mucus layer that covers the stomach lining, allowing the acid and pepsin to erode the tissue and create an ulcer.

– Pepsinogen, as a precursor to pepsin, plays a role in the formation and healing of stomach ulcers. When the stomach lining is injured, the gastric chief cells may secrete more pepsinogen, which is then converted into pepsin by the low pH of the gastric juice. Pepsin can further aggravate the ulcer by digesting the exposed proteins of the stomach wall. However, pepsinogen can also help to heal the ulcer by stimulating the growth of new cells and blood vessels in the ulcerated area.

– Therefore, pepsinogen is related to stomach ulcers in different ways, depending on the balance between its damaging and healing effects. Pepsinogen is essential for the normal digestion of proteins, but when it is dysregulated, it can cause or worsen stomach ulcers. Treatment for stomach ulcers may include medications that reduce the amount of acid and pepsin in the stomach, such as proton pump inhibitors (PPIs) and antacids, as well as antibiotics that eradicate H. pylori infection.