Robuta

https://pmc.ncbi.nlm.nih.gov/articles/PMC21759/ Aminophosphinic inhibitors as transition state analogues of enkephalin-degrading enzymes: A class... Inhibition of aminopeptidase N and neutral endopeptidase-24.11, two zinc metallopeptidases involved in the inactivation of the opioid peptides enkephalins,... transition state analogues