title: Carboxylate-imidazole cooperativity in dipeptide-functionalized gold nanoparticles with esterase-like activity.
abstract: We report here the first example of peptide-functionalized gold nanoparticles hydrolytically active against carboxylate esters. The active units are constituted by His-Phe-OH terminating thiols. The confinement of the catalytic units in the monolayer covering the nanoparticles triggers a cooperative hydrolytic mechanism operative at pH < 7 in which a carboxylate and an imidazolium ion act as general base and general acid, respectively. Such a mechanism is absent with an analogous monomeric dipeptide, and this results in a more than 300-fold rate acceleration of the hydrolytic process at low pH in the presence of the functional nanoparticles.
authors.affiliation: University of Padua, Department of Chemical Sciences and ITM-CNR, Padua Section, 35131 Padua, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Pengo
authors.forename: Stefano
authors.initials: S
authors.lastname: Polizzi
authors.forename: Lucia
authors.initials: L
authors.lastname: Pasquato
authors.forename: Paolo
authors.initials: P
authors.lastname: Scrimin
mesh_terms: D002087:Butyrates / Q000737:chemistry*; D004136:Dinitrobenzenes / Q000737:chemistry; D004151:Dipeptides / Q000737:chemistry*; D004950:Esterases / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry*; D007700:Kinetics; D007930:Leucine / Q000031:analogs & derivatives; D049329:Nanostructures / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000737:chemistry
chemical_list: D002087:Butyrates; D004136:Dinitrobenzenes; D004151:Dipeptides; D007093:Imidazoles; D013438:Sulfhydryl Compounds; D006046:Gold; D004950:Esterases; D007930:Leucine