title: There is no universal mechanism for the cleavage of RNA model compounds in the presence of metal ion catalysts.
abstract: The transesterification of uridine 3'-phosphodiesters with a wide range of leaving group alcohols has been studied in the presence of monometallic and bimetallic complexes. The catalysis of isomerization of the phosphodiester bond was studied with a nucleoside 3'-phosphonate as a substrate. The results obtained are consistent with a step-wise mechanism, where metal ions are able to enhance both the nucleophilic attack and the departure of the leaving group. The mechanism of the catalysis depends on the acidity of the catalyst and of the leaving group alcohol: a change from general base catalysis to general acid catalysis is proposed. Catalysis of the isomerization requires efficient stabilization of the phosphorane by strong interactions with the catalyst. Catalytic strategies utilised by bimetallic complexes are also briefly discussed.
authors.affiliation: University of Turku, Department of Chemistry, FIN-20014 Turku, Finland. satu.mikkola@utu.fi.
authors.forename: Heidi
authors.initials: H
authors.lastname: Korhonen
authors.forename: Timo
authors.initials: T
authors.lastname: Koivusalo
authors.forename: Suvi
authors.initials: S
authors.lastname: Toivola
authors.forename: Satu
authors.initials: S
authors.lastname: Mikkola
mesh_terms: D015082:2,2'-Dipyridyl / Q000737:chemistry; D002384:Catalysis; D056831:Coordination Complexes / Q000737:chemistry; D007536:Isomerism; D010755:Organophosphates / Q000737:chemistry*; D012313:RNA / Q000737:chemistry*; D014529:Uridine / Q000031:analogs & derivatives*; D015032:Zinc / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D010755:Organophosphates; D015082:2,2'-Dipyridyl; D012313:RNA; D015032:Zinc; D014529:Uridine