[Show abstract][Hide abstract] ABSTRACT: 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-gamma-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 microM. 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.
[Show abstract][Hide abstract] ABSTRACT: A series of putative dipeptide substrates of prostate-specific membrane antigen (PSMA) was prepared that explored alpha- and beta/gamma-linked acidic residues at the P1 position and various chromophores at the P2 position, while keeping the P1' residue constant as L-Glu. Four chromophores were examined, including 4-phenylazobenzoyl, 1-pyrenebutyryl, 9-anthracenylcarboxyl-gamma-aminobutyryl, and 4-nitrophenylbutyryl. When evaluating these chromophores, it was found that a substrate containing 4-phenylazobenzoyl at the P2 position was consumed most efficiently. Substitution at the P1 position with acidic residues showed that only gamma-linked L-Glu and D-Glu were recognized by the enzyme, with the former being more readily proteolyzed. Lastly, binding modes of endogenous substrates and our best synthetic substrate (4-phenylazobenzoyl-Glu-gamma-Glu) were proposed by computational docking studies into an X-ray crystal structure of the PSMA extracellular domain.