Design and synthesis of prolylcarboxypeptidase (PrCP) inhibitors to validate PrCP as a potential target for obesity.

Prolylcarboxypeptidase (PrCP) is a serine protease that may have a role in metabolism regulation. A class of reversible, potent, and selective PrCP inhibitors was developed starting from a mechanism based design for inhibiting this serine protease. Compound 8o inhibits human and mouse PrCP at IC(50) values of 1 and 2 nM and is not active (IC(50) > 25 µM) against a panel of closely related proteases. It has lower serum binding than its close analogues and is bioavailable in mouse. Subchronic dosing of 8o in PrCP(-/-) and WT mice at 100 mg/kg for 5 days resulted in a 5% reduction in body weight in WT mice and a 1% reduction in PrCP KO mice.

Peptidomic profiling of human cerebrospinal fluid identifies YPRPIHPA as a novel substrate for prolylcarboxypeptidase.

Prolylcarboxypeptidase (PRCP) is a serine protease that catalyzes the cleavage of C-terminal amino acids linked to proline in peptides. It is ubiquitously expressed and is involved in regulating blood pressure, proliferation, inflammation, angiogenesis, and weight maintenance. To identify the candidate proximal target engagement markers for PRCP inhibition in the central nervous system, we profiled the peptidome of human cerebrospinal fluid to look for PRCP substrates using a MS-based in vitro substrate profiling assay. These experiments identified a single peptide, with the sequence YPRPIHPA, as a novel substrate for PRCP in human cerebrospinal fluid. The peptide YPRPIHPA is from the extracellular portion of human endothelin B receptor-like protein 2.

Discovery of potent and selective dipeptidyl peptidase IV inhibitors derived from beta-aminoamides bearing subsituted triazolopiperazines.

A series of beta-aminoamides bearing triazolopiperazines have been discovered as potent, selective, and orally active dipeptidyl peptidase IV (DPP-4) inhibitors by extensive structure-activity relationship (SAR) studies around the triazolopiperazine moiety. Among these, compound 34b with excellent in vitro potency (IC50 = 4.3 nM) against DPP-4, high selectivity over other enzymes, and good pharmacokinetic profiles exhibited pronounced in vivo efficacy in an oral glucose tolerance test (OGTT) in lean mice. On the basis of these properties, compound 34b has been profiled in detail. Further refinement of the triazolopiperazines resulted in the discovery of a series of extremely potent compounds with subnanomolar activity against DPP-4 (42b- 49b), that is, 4-fluorobenzyl-substituted compound 46b, which is notable for its superior potency (IC50 = 0.18 nM). X-ray crystal structure determination of compounds 34b and 46b in complex with DPP-4 enzyme revealed that (R)-stereochemistry at the 8-position of triazolopiperazines is strongly preferred over (S) with respect to DPP-4 inhibition.

Design, synthesis, and biological evaluation of triazolopiperazine-based beta-amino amides as potent, orally active dipeptidyl peptidase IV (DPP-4) inhibitors.

Various beta-amino amides containing triazolopiperazine heterocycles have been prepared and evaluated as potent, selective, orally active dipeptidyl peptidase IV (DPP-4) inhibitors. These compounds display excellent oral bioavailability and good overall pharmacokinetic profiles in preclinical species. Moreover, in vivo efficacy in an oral glucose tolerance test in lean mice is demonstrated.

Triazolopiperazine-amides as dipeptidyl peptidase IV inhibitors: close analogs of JANUVIA (sitagliptin phosphate).

A series of beta-aminoamides bearing triazolopiperazines has been prepared and evaluated as potent, selective, orally active dipeptidyl peptidase IV (DPP-4) inhibitors. Efforts at optimization of the beta-aminoamide series, which ultimately led to the discovery of JANUVIA (sitagliptin phosphate, compound 1), are described.

Purification, crystallization and preliminary X-ray analysis of Escherichia coli UDP-N-acetylmuramoyl:L-alanine ligase (MurC).

UDP-N-acetylmuramoyl:L-alanine ligase (MurC) is involved in the pathway leading from UDP-N-glucosamine to the UDP-N-acetylmuramoyl:pentapeptide unit, which is the building block for the peptidoglycan layer found in all bacterial cell walls. The pathways leading to the biosynthesis of the peptidoglycan layer are important targets for the development of novel antibiotics, since animal cells do not contain these pathways. MurC is the first of four similar ATP-dependent amide-bond ligases which share primary and tertiary structural similarities. The crystal structures of three of these have been determined by X-ray crystallography, giving insights into the binding of the carbohydrate substrate and the ATP. Diffraction-quality crystals of the enzyme MurC have been obtained in both native and selenomethionine forms and X-ray diffraction data have been collected at the Se edge at a synchrotron source. The crystals are orthorhombic, with unit-cell parameters a = 73.9, b = 93.6, c = 176.8 A, and diffraction has been observed to 2.6 A resolution.

Catalytic properties and inhibition of proline-specific dipeptidyl peptidases II, IV and VII.

There is currently intense interest in the emerging group of proline-specific dipeptidases, and their roles in the regulation of biological processes. Dipeptidyl peptidase IV (DPP-IV) is involved in glucose metabolism by contributing to the regulation of glucagon family peptides and has emerged as a potential target for the treatment of metabolic diseases. Two other proline-specific dipeptidases, DPP-VII (also known as quiescent cell proline dipeptidase) and DPP-II, have unknown functions and have recently been suggested to be identical proteases based on a sequence comparison of human DPP-VII and rat DPP-II (78% identity) [Araki, Li, Yamamoto, Haneda, Nishi, Kikkawa and Ohkubo (2001) J. Biochem. 129, 279-288; Fukasawa, Fukasawa, Higaki, Shiina, Ohno, Ito, Otogoto and Ota (2001) Biochem. J. 353, 283-290]. To facilitate the identification of selective substrates and inhibitors for these enzymes, a complete biochemical profile of these enzymes was obtained. The pH profiles, substrate specificities as determined by positional scanning, Michaelis-Menten constants and inhibition profiles for DPP-VII and DPP-II were shown to be virtually identical, strongly supporting the hypothesis that they are the same protease. In addition, substrate specificities, catalytic constants and IC(50) values were shown to be markedly different from those of DPP-IV. Selective DPP-IV and DPP-VII substrates were identified and they can be used to design selective inhibitors and probe further into the biology of these enzymes.