Inhibitor Report for: Z-Pro-Prolinal

Prolyl peptidases cleave proteins at proline residues and are of importance for cancer, neurological function, and type II diabetes. Prolyl endopeptidase (PEP) cleaves neuropeptides and is a drug target for neuropsychiatric diseases such as post-traumatic stress disorder, depression, and schizophrenia. Previous structural analyses showing little differences between native and substrate-bound structures have suggested a lock-and-key catalytic mechanism. We now directly demonstrate from seven structures of Aeromonus punctata PEP that the mechanism is instead induced fit: the native enzyme exists in a conformationally flexible opened state with a large interdomain opening between the beta-propeller and alpha/beta-hydrolase domains; addition of substrate to preformed native crystals induces a large scale conformational change into a closed state with induced-fit adjustments of the active site, and inhibition of this conformational change prevents substrate binding. Absolute sequence conservation among 28 orthologs of residues at the active site and critical residues at the interdomain interface indicates that this mechanism is conserved in all PEPs. This finding has immediate implications for the use of conformationally targeted drug design to improve specificity of inhibition against this family of proline-specific serine proteases.

Prolyl oligopeptidase, a member of a new family of serine peptidases, plays an important role in memory disorders. Earlier x-ray crystallographic investigations indicated that stabilization of the tetrahedral transition state of the reaction involved hydrogen bond formation between the oxyanion of the tetrahedral intermediate and the OH group of Tyr(473). The contribution of the OH group was tested with the Y473F variant using various substrates. The charged succinyl-Gly-Pro-4-nitroanilide was hydrolyzed with a much lower k(cat)/K(m) compared with the neutral benzyloxycarbonyl-G1y-Pro-2-naphthylamide, although the binding modes of the two substrates were similar, as shown by x-ray crystallography. This suggested that electrostatic interactions between Arg(643) and the succinyl group competed with the productive binding mechanism. Unlike most enzyme reactions, catalysis by the wild-type enzyme exhibited positive activation entropy. In contrast, the activation entropy for the Y473F variant was negative, suggesting that the tyrosine OH group is involved in stabilizing both the transition state and the water shell at the active site. Importantly, Tyr(473) is also implicated in the formation of the enzyme-substrate complex. The nonlinear Arrhenius plot suggested a greater significance of the oxyanion binding site at physiological temperature. The results indicated that Tyr(473) was more needed at high pH, at high temperature, and with charged substrates exhibiting "internally competitive inhibition.

Prolyl oligopeptidase is a large cytosolic enzyme that belongs to a new class of serine peptidases. The enzyme is involved in the maturation and degradation of peptide hormones and neuropeptides, which relate to the induction of amnesia. The 1.4 A resolution crystal structure is presented here. The enzyme contains a peptidase domain with an alpha/beta hydrolase fold, and its catalytic triad (Ser554, His680, Asp641) is covered by the central tunnel of an unusual beta propeller. This domain makes prolyl oligopeptidase an oligopeptidase by excluding large structured peptides from the active site. In this way, the propeller protects larger peptides and proteins from proteolysis in the cytosol. The structure is also obtained with a transition state inhibitor, which may facilitate drug design to treat memory disorders.

Prolyl oligopeptidases (POPs) are atypical serine proteases that are unique in their involvement in the maturation and degradation of prolyl-containing peptide hormones and neuropeptides. They are potential pharmaceutical targets for the treatment of several neurodegenerative disorders, such as Alzheimer's disease. In this study, the catalytic and substrate-regulatory mechanisms of a novel bacterial POP from Microbulbifer arenaceous (MaPOP) were investigated. The crystal structure revealed that the catalytic triad of MaPOP was covered by the central tunnel of an unusual beta-propeller domain. The tunnel not only provided the sole access to the active site for oligopeptides, but also protected large structured peptides or proteins from accidental proteolysis. The enzyme was able to cleave angiotensin I specifically at the carboxyl side of the internal proline residue, but could not hydrolyze long-chain bovine insulin B in vitro. Like the ligand-free structure, MaPOP bound to the transition-state analog inhibitor ZPR was also in a closed state, which was not modulated by the common `latching loop' found in other POPs. The substrate-assisted catalytic mechanism of MaPOP reported here may represent a common mechanism for all POPs. These results may facilitate a better understanding of the catalytic behavior of POPs under physiological conditions.

Prolyl peptidases cleave proteins at proline residues and are of importance for cancer, neurological function, and type II diabetes. Prolyl endopeptidase (PEP) cleaves neuropeptides and is a drug target for neuropsychiatric diseases such as post-traumatic stress disorder, depression, and schizophrenia. Previous structural analyses showing little differences between native and substrate-bound structures have suggested a lock-and-key catalytic mechanism. We now directly demonstrate from seven structures of Aeromonus punctata PEP that the mechanism is instead induced fit: the native enzyme exists in a conformationally flexible opened state with a large interdomain opening between the beta-propeller and alpha/beta-hydrolase domains; addition of substrate to preformed native crystals induces a large scale conformational change into a closed state with induced-fit adjustments of the active site, and inhibition of this conformational change prevents substrate binding. Absolute sequence conservation among 28 orthologs of residues at the active site and critical residues at the interdomain interface indicates that this mechanism is conserved in all PEPs. This finding has immediate implications for the use of conformationally targeted drug design to improve specificity of inhibition against this family of proline-specific serine proteases.

Prolyl oligopeptidase, a member of a new family of serine peptidases, plays an important role in memory disorders. Earlier x-ray crystallographic investigations indicated that stabilization of the tetrahedral transition state of the reaction involved hydrogen bond formation between the oxyanion of the tetrahedral intermediate and the OH group of Tyr(473). The contribution of the OH group was tested with the Y473F variant using various substrates. The charged succinyl-Gly-Pro-4-nitroanilide was hydrolyzed with a much lower k(cat)/K(m) compared with the neutral benzyloxycarbonyl-G1y-Pro-2-naphthylamide, although the binding modes of the two substrates were similar, as shown by x-ray crystallography. This suggested that electrostatic interactions between Arg(643) and the succinyl group competed with the productive binding mechanism. Unlike most enzyme reactions, catalysis by the wild-type enzyme exhibited positive activation entropy. In contrast, the activation entropy for the Y473F variant was negative, suggesting that the tyrosine OH group is involved in stabilizing both the transition state and the water shell at the active site. Importantly, Tyr(473) is also implicated in the formation of the enzyme-substrate complex. The nonlinear Arrhenius plot suggested a greater significance of the oxyanion binding site at physiological temperature. The results indicated that Tyr(473) was more needed at high pH, at high temperature, and with charged substrates exhibiting "internally competitive inhibition.

Prolyl oligopeptidase is a large cytosolic enzyme that belongs to a new class of serine peptidases. The enzyme is involved in the maturation and degradation of peptide hormones and neuropeptides, which relate to the induction of amnesia. The 1.4 A resolution crystal structure is presented here. The enzyme contains a peptidase domain with an alpha/beta hydrolase fold, and its catalytic triad (Ser554, His680, Asp641) is covered by the central tunnel of an unusual beta propeller. This domain makes prolyl oligopeptidase an oligopeptidase by excluding large structured peptides from the active site. In this way, the propeller protects larger peptides and proteins from proteolysis in the cytosol. The structure is also obtained with a transition state inhibitor, which may facilitate drug design to treat memory disorders.