The structure of the synthetic protected dipeptide (Z)-Pro- Leuol [systemat
ic name: benzyl 2-(1-hydroxymethyl-3-methylbutylaminocarbonyl)pyrrolidine-1
-carboxylate], C19H28N2O4, was determined by X-ray crystallography. The pep
tide adopts a novel backbone conformation compared with other longer oligop
eptides containing Pro-Leuol.