Prolylcarboxypeptidase (PrCP) is a serine protease that may have a role in metabolism regulation. A class of reversible, potent, and selective PrCP inhibitors was developed starting from a mechanism based design for inhibiting this serine protease. Compound 8o inhibits human and mouse PrCP at IC50 values of 1 and 2 nM and is not active (IC50> 25 μM) against a panel of closely related proteases. It has lower serum binding than its close ...