title: Ribonuclease Activity of an Artificial Catalyst That Combines a Ligated Cu(II) Ion and a Guanidinium Group at the Upper Rim of a cone-Calix[4]arene Platform.
abstract: A cone-calix[4]arene derivative, featuring a guanidinium group and a Cu(II) ion ligated to a 1,4,7-triazacyclononane (TACN) ligand at the 1,3-distal positions of the upper rim, effectively catalyzes the cleavage of 2-hydroxypropyl p-nitrophenyl phosphate (HPNP) and a number of diribonucleoside 3',5'-monophosphates (NpN'). Kinetic and potentiometric measurements support the operation of a general-base/general-acid mechanism and demonstrate that the hydroxo form of the ligated Cu(II) ion is the sole catalytically active species. Rate enhancements relative to the background hydrolysis reaction at 1 mM catalyst concentration are 6 × 10(5)-fold for HPNP and cluster around 10(7)-fold with the most favorable catalyst-NpN' combinations.
authors.affiliation: †Dipartimento di Chimica and IMC-CNR Sezione Meccanismi di Reazione, Università La Sapienza, 00185 Roma, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Salvio
authors.affiliation: ‡Dipartimento di Chimica, Università degli Studi di Parma, Viale delle Scienze 17/A, 43124 Parma, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Volpi
authors.affiliation: †Dipartimento di Chimica and IMC-CNR Sezione Meccanismi di Reazione, Università La Sapienza, 00185 Roma, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Cacciapaglia
authors.affiliation: ‡Dipartimento di Chimica, Università degli Studi di Parma, Viale delle Scienze 17/A, 43124 Parma, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Casnati
authors.affiliation: †Dipartimento di Chimica and IMC-CNR Sezione Meccanismi di Reazione, Università La Sapienza, 00185 Roma, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Mandolini
authors.affiliation: ‡Dipartimento di Chimica, Università degli Studi di Parma, Viale delle Scienze 17/A, 43124 Parma, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Sansone
mesh_terms: D001669:Biochemical Phenomena; D047250:Calixarenes / Q000737:chemistry*; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D019791:Guanidine / Q000737:chemistry*; D006571:Heterocyclic Compounds / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D010755:Organophosphates; D010636:Phenols / Q000737:chemistry*; D012260:Ribonucleases / Q000737:chemistry*; D012263:Ribonucleosides / Q000737:chemistry*
chemical_list: C436487:2-(hydroxypropyl)-4-nitrophenyl phosphate; D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; D010755:Organophosphates; D010636:Phenols; D012263:Ribonucleosides; C121325:calix(4)arene; D047250:Calixarenes; C075712:1,4,7-triazacyclononane; D003300:Copper; D012260:Ribonucleases; D019791:Guanidine