T. C. Bruice, A. Tsubouchi, R. Dempcy
Oct 16, 1996
Citations
0
Influential Citations
67
Citations
Journal
Journal of the American Chemical Society
Abstract
Adenosine 3‘-O(PO2-)OCH2R phosphate esters have been synthesized with R = 8-hydroxyquinol-2-yl (1a) and 8-(hydroxyquinolyl)-2-methylene (1b). The adenosine 3‘-O(PO2-)OCH2R structure has the essential features of an RNA dinucleotide. Equilibrium binding studies with metal ions Mg2+, Zn2+, Cu2+, and La3+ have been carried out with 1a, 1b, HOCH2R (7a and 7b), and 8-hydroxyquinoline (8), and equilibrium constants (Kas) have been determined for the formation of 1:1 (L)Mn+ complexes. The hydrolysis of 1a and 1b as well as (1a)Mn+ and (1b)Mn+ species are first order in HO-. The rate enhancement for hydrolysis of 1a by complexation with metal ions is as follows: ∼105 with Zn2+, ∼103 with Mg2+, ∼105 with Cu2+, and ∼109 with La3+. Molecular modeling indicates that metal ions ligated to the 8-hydroxyquinoline moiety in the complexes (1a)Mn+ and (1b)Mn+ catalyze 1a and 1b hydrolysis by interacting as Lewis acid catalysts with the negatively charged oxygen atom of the phosphate group. In the instance of La3+ complexe...