Enteropeptidase

protease, serine, 7 (enteropeptidase)
Crystal structure of Enteropeptidase with an inhibitor
Identifiers
Symbol	PRSS7
Entrez	5651
HUGO	9490
OMIM	606635
RefSeq	NM_002772
UniProt	P98073
Other data
Locus	Chr. 21 q21

Enteropeptidase (also called enterokinase) is an enzyme involved in human digestion. It is produced by cells in the duodenum wall, and is secreted from duodenum's glands, the crypts of Lieberkühn, whenever ingested food enters the duodenum from the stomach. Enteropeptidase has the critical job of turning trypsinogen (a zymogen) to trypsin, indirectly activating a number of pancreatic digestive enzymes.

Enteropeptidase is a serine protease enzyme (EC 3.4.21.9). Enteropeptidase is a part of the Chymotrypsin-clan of serine proteases, and is structurally similar to these proteins.

Reaction

The reaction catalysed by Enteropeptidase:

trypsinogen → trypsin + hexapeptide

Val--(Asp)₄--Lys--Ile--Val~ (trypsinogen) → Val--(Asp)₄--Lys (hexapeptide) + Lys--Ile--Val~ (trypsin)

Enteropeptidase cleaves after Lysine if the Lys is preceded by four Asp and not followed by a Pro. ^[1]

Nomenclature

Despite its older name of enterokinase, the enzyme is not a kinase. This is because enteropeptidase alters the degree of enzymatic activity its substrate expresses though a proteolytic cleavage reaction. A kinase would do the same by phosphorylation reaction.

Genetics

Enteropeptidase is encoded by the PRSS7 (serine protease-7 gene) or ENTK gene on the 21st chromosome (21q21).

Isolated cases of enteropeptidase deficiency have been reported.^[2]

References

1. ^ "Enterokinase, light chain (P8070), Proteases, NEB". http://www.neb.com/nebecomm/products/productP8070.asp. Retrieved 2007-10-04. 
2. ^ Holzinger A, Maier EM, Bück C, et al. (2002). "Mutations in the proenteropeptidase gene are the molecular cause of congenital enteropeptidase deficiency". Am. J. Hum. Genet. 70 (1): 20–5. doi:10.1086/338456. PMID 11719902. 

External links

• MeSH Enteropeptidase