Enteropeptidase or enterokinase is an enzymeinvolved in human digestion. It is produced by cells in the duodenum wall, and is secreted from duodenum's glands, the crypts of Lieberk?hn, 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 pancreaticdigestive enzymes.

Enteropeptidase is a serine proteaseenzyme(EC3.4.21.9). Enteropeptidase is a part of the Chymotrypsin-clan of serine proteases, and is structurally similar to these proteins.

Enteropeptidase Human is a specific protease that cleaves after the sequence

Asp-Asp-Aps-Aps-Lys. The light chain of enteropeptidase has full enzymatic activity. No other protease activity was detected. Human enteropeptidase binds specifically to STI-agarose. The affinity puirifed Human Enterokinase contains amino acids from 785 to 1019.