title: Structure-guided, single-point modifications in the phosphinic dipeptide structure yield highly potent and selective inhibitors of neutral aminopeptidases.
abstract: Seven crystal structures of alanyl aminopeptidase from Neisseria meningitides (the etiological agent of meningitis, NmAPN) complexed with organophosphorus compounds were resolved to determine the optimal inhibitor-enzyme interactions. The enantiomeric phosphonic acid analogs of Leu and hPhe, which correspond to the P1 amino acid residues of well-processed substrates, were used to assess the impact of the absolute configuration and the stereospecific hydrogen bond network formed between the aminophosphonate polar head and the active site residues on the binding affinity. For the hPhe analog, an imperfect stereochemical complementarity could be overcome by incorporating an appropriate P1 side chain. The constitution of P1'-extended structures was rationally designed and the lead, phosphinic dipeptide hPhePψ[CH2]Phe, was modified in a single position. Introducing a heteroatom/heteroatom-based fragment to either the P1 or P1' residue required new synthetic pathways. The compounds in the refined structure were low nanomolar and subnanomolar inhibitors of N. meningitides, porcine and human APNs, and the reference leucine aminopeptidase (LAP). The unnatural phosphinic dipeptide analogs exhibited a high affinity for monozinc APNs associated with a reasonable selectivity versus dizinc LAP. Another set of crystal structures containing the NmAPN dipeptide ligand were used to verify and to confirm the predicted binding modes; furthermore, novel contacts, which were promising for inhibitor development, were identified, including a π-π stacking interaction between a pyridine ring and Tyr372.
authors.affiliation: Laboratory of Organic Chemistry, Department of Chemistry, University of Athens , Panepistimiopolis, Zografou, 15701 Athens, Greece.
authors.forename: Stamatia
authors.initials: S
authors.lastname: Vassiliou
authors.forename: Ewelina
authors.initials: E
authors.lastname: Węglarz-Tomczak
authors.forename: Łukasz
authors.initials: Ł
authors.lastname: Berlicki
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Pawełczak
authors.forename: Bogusław
authors.initials: B
authors.lastname: Nocek
authors.forename: Rory
authors.initials: R
authors.lastname: Mulligan
authors.forename: Andrzej
authors.initials: A
authors.lastname: Joachimiak
authors.forename: Artur
authors.initials: A
authors.lastname: Mucha
mesh_terms: D000626:Aminopeptidases / Q000037:antagonists & inhibitors*; D001665:Binding Sites; D015195:Drug Design; D006801:Humans; D007931:Leucyl Aminopeptidase / Q000037:antagonists & inhibitors; D011480:Protease Inhibitors / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D013329:Structure-Activity Relationship
chemical_list: D011480:Protease Inhibitors; D000626:Aminopeptidases; D007931:Leucyl Aminopeptidase