Synthesis of some amino and carboxy analogs of galabiose; evaluation as inhibitors of the pilus protein PapGJ96 from Escherichia coli

The 2′-amino-2′-deoxy, 6-amino-6-deoxy, and 6-carboxy analogs of the reference inhibitor 2-(trimethylsilyl)ethyl (α-d-galactopyranosyl)-(1→4)-β-d-galactopyranoside were synthesized and evaluated as inhibitors of the binding of the Escherichia coli-derived pilus protein PapGJ96, using an ELISA assay. The inhibitory efficiencies (Krel; relative to the reference inhibitor) were: 157, 13, and <8, respectively. The results support the previously proposed combining site model, where the protein carries a negatively charged amino acid residue near HO-2′ and HO-6 of the galabioside.