Mechanism and inhibition of prolidase.

The pH dependence of Ki for inhibition of prolidase by acetylproline, proline, and trans-1,2-cyclopentanedicarboxylate follows a different pattern in each case, although deprotonation of an enzymic functional group with a pKa value of 6.6 perturbs ligand binding in every instance. Results are most easily explained with prolidase active as a metalloenzyme dimer exhibiting selective cooperative interactions.