A structural insight into the P1 S1 binding mode of diaminoethylphosphonic and phosphinic acids, selective inhibitors of alanine aminopeptidases

Abstract

N'-substituted 1,2-diaminoethylphosphonic acids and 1,2-diaminoethylphosphinic dipeptides were explored to unveil the structural context of the unexpected selectivity of these inhibitors of M1 alanine aminopeptidases (APNs) versus M17 leucine aminopeptidase (LAP). The diaminophosphonic acids were obtained via aziridines in an improved synthetic procedure that was further expanded for the phosphinic pseudodipeptide system. The inhibitory activity, measured for three M1 and one M17 metalloaminopeptidases of different sources (bacterial, human and porcine), revealed several potent compounds (e.g., Ki = 65 nM of 1u for HsAPN). Two structures of an M1 representative (APN from Neisseria meningitidis) in complex with N-benzyl-1,2-diaminoethylphosphonic acid and N-cyclohexyl-1,2-diaminoethylphosphonic acid were determined by the X-ray crystallography. The analysis of these structures and the models of the phosphonic acid complexes of the human ortholog provided an insight into the role of the additional amino group and the hydrophobic substituents of the ligands within the S1 active site region.

Phosphonic Acid Analogs of Fluorophenylalanines as Inhibitors of Human and Porcine Aminopeptidases N: Validation of the Importance of the Substitution of the Aromatic Ring

“…Each experiment was repeated three times and standard deviation values were calculated. The type of the inhibition and inhibitory constants were calculated by using the Lineweaver-Burk, Dixon plot and Cheng-Prusoff equation: K i = IC 50 /[1 + (S/K m )] as described earlier [32]. Kinetics parameters were calculated using GrafPad Prism and Microsoft Excel computer programs.…”

M1 aminopeptidases as drug targets: broad applications or therapeutic niche?

“…Early work to produce the X‐ray crystal structure arose from a structural genomics initiative, and therapeutic utility was extrapolated from reports describing aminopeptidases from pathogenic bacteria as potential drug targets . Extensive substrate profiling experiments characterized Nm APN as possessing a preference for bulky basic and hydrophobic ligands , and a subsequent inhibitor development initiative produced selective compounds with low micromolar potency . However, despite these advances in understanding the enzyme mechanism of activity and inhibition, there is no published literature to support the hypothesis that Nm APN is a valid drug target.…”

Synthesis of Functionalized Novel α‐Amino‐β‐alkoxyphosphonates through Regioselective Ring Opening of Aziridine‐2‐phosphonates

“…As an example, the phosphonic acid analogue of leucine (LeuP) obtained by ring opening reaction of aziridinyl phosphonate with amines is one of the best described inhibitor toward meningococcal ( N. meningitides , NmAPN), human ( H. sapiens APN, HsAPN) and porcine alanyl aminopeptidase ( S. scrofa , SsAPN) and human endoplasmic reticulum aminopeptidase 1 (ERAP1) . Although the literature have many examples to ring opening reactions of aziridine‐2‐carboxylates, the same reaction studied with the aziridine‐2‐phosphonates are limited . Our group is also involved in this field and reported the synthesis of racemic and chiral aziridine‐2‐phosphonates by modified Gabriel–Cromwell reaction and the results of their antibacterial activities .…”