Peptide mimics of glycylproline as inhibitors of prolidase

Aminoketone 1, a ψ[CO---CH] dipeptide mimic of glycylproline, is a potent, competitive inhibitor (Ki = 270 ± 24 nM) of porcine kidney prolidase, a Mn(II)-dependent dipeptidase, whereas the homologous aminoketone 2 and its non-cyclic analogue δ-amino-levulinic acid, 3, are significantly less inhibitory (Ki ≈ 1 mM).