Question

Trypsinogen is secreted by
A. Pancreas
B. Stomach
C. Liver
D. Ileum

Answer 1

Hint: Trypsinogen is the precursor form of a digestive enzyme called trypsin.

Complete Answer:
- It is formed by the pancreas and is contained, along with amylase , lipase, and chymotrypsinogen, in pancreatic juice.
- By enteropeptidase, which is located in the intestinal mucosa, it is cleaved into its active form, trypsin. When activated, more trypsinogen can be cleaved into trypsin, a process called autoactivation, by trypsin. On the carboxyl side of fundamental amino acids such as arginine and lysine, Trypsin cleaves the peptide bond.
- The proenzyme precursor of trypsin is trypsinogen. In the pancreas, trypsinogen (the inactive form) is stored so that it may be released when protein digestion is necessary.
- The inactive form of trypsinogen is maintained by the pancreas because the active trypsin will cause significant damage to the pancreas tissue. The pancreas releases Trypsinogen through the pancreatic duct into the second part of the duodenum along with other digestive enzymes.
- Trypsinogen is activated (also known as enterokinase) by enteropeptidase. Enteropeptidase is formed by the duodenum mucosa and cleaves the trypsinogen peptide bond after residue 15, which is a lysine. The N-terminal peptide is discarded, and the folded protein is rearranged slightly.Inappropriate trypsinogen activation in the pancreas can lead to pancreatitis. Mutant forms of trypsinogen can be associated with a certain type of pancreatitis.

The correct answer is option (A) Pancreas.

Note: In the rough endoplasmic reticulum, Trypsin is synthesised as trypsinogen, an inactive precursor, and transported for sorting to the Golgi apparatus. A pancreatic secretory trypsin inhibitor (PSTI) that inhibits its premature activation is often co-synthesized and packed with Trypsinogen. The trypsinogen and other digestive enzymes condense into core particles until they enter the Golgi system and are wrapped in zymogen granules.