Substrate Report for: Prolyl-2-naphthylamide

Puromycin-hydrolizing peptidases have been described as members of the prolyl oligopeptidase peptidase family. These enzymes are present across all domains of life but still little is known of the homologs found in the pathogenic bacterium Mycobacterium tuberculosis. The crystal structure of a M. tuberculosis puromycin hydrolase peptidase has been determined at 3 Angstrom resolution, revealing a conserved prolyl oligopeptidase fold, defined by alpha/beta-hydrolase and beta-propeller domains with two distinctive loops that occlude access of large substrates to the active site. The enzyme displayed amino peptidase activity with a substrate specificity preference for hydrophobic residues in the decreasing order of phenylalanine, leucine, alanine and proline. The enzyme's active site is lined by residues Glu564 for the coordination of the substrates amino terminal moiety and His561, Val608, Tyr78, Trp306, Phe563 and Ty567 for the accommodation of hydrophobic substrates. The availability of a crystal structure for puromycin hydrolase of M. tuberculosis shall facilitate the development of inhibitors with therapeutic applications. This article is protected by copyright. All rights reserved.

Prolyl-beta-naphthylamidase from porcine liver is compared with the two prevalent isoenzymes of pig liver carboxylesterase by isoelectrofocusing experiments and by inhibition studies with phenyl-methyl-sulfonyl fluoride. The results suggest that prolyl-beta-naphthylamidase is identical with the amide-cleaving isoenzyme of carboxylesterase, not with the usually predominant methyl butyrate-hydrolysing isoenzyme. It is questionable whether the recently published sequence of prolyl-beta-naphthylamidase does belong to this enzyme or to the predominant carboxylesterase without amidase activity. Surprisingly, the amide-cleaving carboxylesterase isoenzymes from rat liver have almost no activity with prolyl-beta-naphthylamide.