The molecular pruning of a phosphoramidate peptidomimetic inhibitor of prostate-specific membrane antigen

To identify the pharmacophore of a phosphoramidate peptidomimetic inhibitor of prostate-specific membrane antigen (PSMA), a small analog library was designed and screened for inhibitory potency against PSMA. The design of the lead inhibitor was based upon N-acyl derivatives of endogenous substrate folyl-γ-Glu and incorporates a phosphoramidate group to interact with the PSMA catalytic zinc atoms. The scope of the analog library was designed to test the importance of various functional groups to the inhibitory potency of the lead phosphoramidate. The IC 50 for the lead phosphoramidate inhibitor was 35 nM while the IC 50 values for the analog library presented a range from 0.86 nM to 4.1 μM. Computational docking, utilizing a recently solved X-ray crystal structure of the recombinant protein, along with enzyme inhibition data, was used to propose a pharmacophore model for the PSMA active site.