Members of this family represent a distinctive subset within the zinc metallopeptidase family M1 (pfam01433). The majority of the members of pfam01433 are aminopeptidases, but the sequences in this family for which the function is known are leukotriene A-4 hydrolase. A dual epoxide hydrolase and aminopeptidase activity at the same active site is indicated. The physiological substrate for aminopeptidase activity is not known.