Enterokinase

enteropeptidase
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Crystal structure of Enteropeptidase with an inhibitor
Identifiers
EC number CAS number IntEnz BRENDA ExPASy KEGG MetaCyc metabolic pathway
PRIAM PDB structures PDBsum
Gene Ontology EGO
protease, serine, 7 (enteropeptidase)
Identifiers
Symbol PRSS7
Entrez HUGO OMIM RefSeq UniProt Locus q21

Enteropeptidase (also called enterokinase) is an enzyme produced by cells of the duodenum and involved in human digestion. It is secreted from intestinal glands (the crypts of Lieberkühn) following the entry of ingested food passing from the stomach. Enteropeptidase converts trypsinogen (a zymogen) into its active form trypsin, resulting in the subsequent activation of pancreatic digestive enzymes.[1][2]

Enteropeptidase is a

Activity

Despite its alternative name, enteropeptidase is a serine protease that catalyses the hydrolysis of peptide bonds in proteins. Enteropeptidase exhibits trypsin-like activity, cleaving proteins following a lysine at a specific cleavage site (Asp-Asp-Asp-Asp-Lys).[5] As the pro-region of trypsinogen contains this sequence, enteropeptidase catalyses its activation in vivo:

trypsinogen → trypsin + pro-region (Val-Asp-Asp-Asp-Asp-Lys)

Genetics

In humans, enteropeptidase is encoded by the PRSS7 gene (also known as ENTK) on chromosome 21q21. Some nonsense and frameshift mutations in this gene lead to a rare recessive disorder characterised by severe failure to thrive in affected infants, due to enteropeptidase deficiency.[6]

Applications

Enteropeptidase's specificity makes it an ideal tool in biochemical applications; a fusion protein containing a C-terminal affinity tag (such as poly-His) linked by this sequence can be cleaved by enteropeptidase to obtain the target protein following protein purification.[5] On the converse, the N-terminal pro-sequence of proteases that must be cleaved prior to activation can be mutated to enable activation with enteropeptidase.[7]

References

External links

  • Medical Subject Headings (MeSH)