Lipohexin, a new inhibitor of prolyl endopeptidase from Moeszia lindtneri (HKI-0054) and Paecilomyces sp. (HKI-0055; HKI-0096). II. Inhibitory activities and specificity

The new proline-containing lipohexapeptide lipohexin (I) isolated from three fungal strains, Moeszia lindtneri (HKI-0054) and Paecilomyces sp. (HKI-0055 and HKI-0096) is a competitive inhibitor of prolyl endopeptidase (PEP) from human placenta with IC50 of 3.5 microM. Specificity of lipohexin (I) is indicated by the much weaker inhibitory activity against bacterial prolyl endopeptidase from Flavobacterium meningosepticum (IC50 25 microM). No effect of lipohexin (I) was found on the activity of mechanistically related proteases such as proline specific proteases and other serine proteases.