Endopeptidase activity of the brush border of human enterocyte

Succinyl-trialanine-p-nitroanilide (Suc-Ala3-pNA) has been described earlier as a convenient substrate for pancreatic elastase which is not split by trypsin and chymotrypsin. An enzyme activity splitting Suc-Ala3-pNA has been found in the supernatant of the mucous membrane of human small intestine homogenized with Triton X-100.