Converts big endothelin-1 to endothelin-1. Also involved in the processing of various neuroendocrine peptides, including neurotensin, angiotensin I, substance P, proenkephalin-derived peptides, and prodynorphin-derived peptides (By similarity). May play a role in amyloid-beta processing (PubMed:12464614). Hydrolysis of the 21-Trp-|-Val-22 bond in big endothelin to form endothelin 1. Binds 1 zinc ion per subunit. Eef1akmt4-Ece2 and Ece2 double mutant mice are fertile and healthy, and do not display any abnormality in terms of growth or aging. Belongs to the peptidase M13 family.