enteropeptydaz

Enteropeptydaz, also known as enteropeptidase or enterokinase, is a serine protease enzyme that plays a key role in initiating protein digestion. It is produced by cells of the small-intestinal mucosa, particularly on the brush border of enterocytes, and is typically present in an inactive zymogen form that becomes active in the intestinal lumen.

Biological function and mechanism: Enteropeptydaz is responsible for activating pancreatic zymogens by cleaving the N-terminal activation peptide of trypsinogen, converting it into active trypsin. Active trypsin then activates other pancreatic enzymes, such as chymotrypsinogen and procarboxypeptidases, thereby starting the proteolytic cascade that enables protein digestion. The enzyme recognizes a specific activation motif, commonly a sequence ending in DDDDK (Asp-Asp-Asp-Asp-Lys) in trypsinogen.

Structure and localization: In humans, enteropeptidase is a membrane-associated serine protease anchored to the intestinal mucosal surface. It is synthesized as an inactive precursor and undergoes proteolytic processing to attain its active form, after which it remains associated with the brush border.

Clinical relevance: Congenital enteropeptidase deficiency is rare but can cause fat malabsorption and failure to thrive due to impaired activation of pancreatic enzymes. Diagnosis is based on clinical suspicion and laboratory assessment of enzyme activity; treatment often involves pancreatic enzyme replacement therapy to aid digestion.

Biotechnological use: Enteropeptidase is widely used in molecular biology to remove affinity or purification tags from recombinant proteins. The enzyme cleaves after the recognition sequence DDDDK, enabling precise tag removal in protein engineering workflows.

See also: trypsin, trypsinogen, pancreatic zymogens, digestion.