一种蛋白酶。属于肽链端解酶，可使氨基酸从多肽链的N-末端顺序逐个地游离出来。在许多生物中发现了各种性质的这种酶。具有代表性的是亮氨酸氨肽酶，特殊的有仅作用于N末端为脯氨酸的脯氨酸亚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.