一種蛋白酶。屬于肽鏈端解酶，可使氨基酸從多肽鏈的N-末端順序逐個地游離出來。在許多生物中發現了各種性質的這種酶。具有代表性的是亮氨酸氨肽酶，特殊的有僅作用于N末端為脯氨酸的脯氨酸亞氨肽酶以及只作用于三肽的氨基三肽酶等。

A protease. It belongs to peptide chain end-lyase, which can free amino acids from n-terminal sequence of polypeptide chain. Various properties of this enzyme have been found in many organisms. The representative ones are leucine aminopeptidase, especially proline iminopeptidase which only acts on N-terminal proline and amino tripeptidase which only acts on tripeptide.