title: Upper Rim Bifunctional cone-Calix[4]arenes Based on a Ligated Metal Ion and a Guanidinium Unit as DNAase and RNAase Mimics.
abstract: The catalytic activity of an artificial phosphodiesterase that combines a ligated metal ion (Cu(II), Zn(II)) with a guanidinium unit connected by a 1,2-vicinal calix[4]arene spacer was investigated in the transesterification of RNA models HPNP and four diribonucleoside 3',5'-monophosphates. Comparison with previous data related to the 1,3-distal regioisomeric metal complexes confirms the superiority of the Cu(II) complexes over the Zn(II) analogs and shows that in the reactions of HPNP, GpU, and UpU, the catalytic efficiency depends very little on whether the substitution pattern is 1,2-vicinal or 1,3-distal. On the other hand, CpA turned out to be a good substrate for the Cu(II) complex of the 1,2-vicinal catalyst and a bad substrate for the corresponding 1,3-distal regioisomer, whereas the opposite holds for GpA. Extension of the investigation to the cleavage of the DNA model BNPP showed that both Zn(II) and Cu(II) complexes exhibit good catalytic efficiency, with a superiority of the 1,2-vicinal catalyst in both cases. The data reported in this work show that rate accelerations over background for the best catalyst-substrate combinations at 0.5 mM catalyst concentration are 3.6 × 10(5)-fold for HPNP, 1.1 × 10(6)-fold for BNPP, and range from 1.3 × 10(6)- to 1.3 × 10(7)-fold for diribonucleoside monophosphates.
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 , Parco Area 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 , Parco Area delle Scienze 17/a, 43124 Parma, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Sansone
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 , Parco Area delle Scienze 17/a, 43124 Parma, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Casnati
mesh_terms: D047250:Calixarenes / Q000138:chemical synthesis / Q000737:chemistry*; D002384:Catalysis; D056831:Coordination Complexes / Q000737:chemistry; D018360:Crystallography, X-Ray; D003851:Deoxyribonucleases / Q000737:chemistry*; D019791:Guanidine / Q000737:chemistry*; D007202:Indicators and Reagents; D007700:Kinetics; D008024:Ligands; D008958:Models, Molecular; D018716:Molecular Mimicry; D011199:Potentiometry; D012260:Ribonucleases / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D056831:Coordination Complexes; D007202:Indicators and Reagents; D008024:Ligands; D047250:Calixarenes; D003851:Deoxyribonucleases; D012260:Ribonucleases; D019791:Guanidine