human diseases, the existing studies are promising but not yet as developed as for the ACE. Some examples are: a) the POP of nervous tissues has been suggested to be involved in neuropsychiatric disorders, like in post-traumatic stress, depression, mania, nervous bulimia, anorexia, and schizophrenia, as reviewed in. b) NEP has been involved in cancer; c) the TOP has been involved in tuberculosis and in cancer; d) the EOPA or NUDEL/EOPA (NDEL1/EOPA gene product) has been involved in neuronal migration during the cortex formation in human embryo (lissencephaly) and neurite outgrowth in adults, as in schizophrenia. Coincidentally, an activity related to the development of nervous tissue has been suggested for POP, nevertheless not involving its proteolytic activity. The absence of an oligopeptidase in the intestine was also responsible for the decreased serum zinc levels observed in patients who have the disease Acrodermatitis Enteropathica. References External links The MEROPS online database for peptidases and their inhibitors Hydrolases EC 3.4 Proteases Metabolism Immunology