Cerium(IV) ion efficiently hydrolyses the phosphodiester linkages in DNAs, even in the absence of molecular oxygen. The pseudo first-order rate constant for the hydrolysis of thymidylyl-(3′,5′)thymidine (TpT) by Ce(NH4)2(NO3)6 (0.01 mol dm -3) at pH 7 and 50 °C is 1.9 × 10-1 h -1 (the half-life is 3.6 h), either with or without molecular oxygen. DNA hydrolysis by CeCl3 requires molecular oxygen to convert the CeIII ion to CeIV. Addition of hydrogen peroxide causes various side-reactions rather than accelerating the hydrolysis. The hydrolysis by CeIV proceeds via P-O scission, as confirmed by the absence of 18O incorporation into thymidine (T) during the reaction in an H 218O-H216O mixture. There exists no specific base-preference in the scission, and concurrent oxidative cleavage of the deoxyribose is nil. The activity of CeIV is more than 200 fold greater than those of trivalent lanthanide ions and of other tetravalent ions. A significant D2O solvent isotope effect and the pH independence of the hydrolysis rate indicate that the hydrolysis proceeds via an intramolecular attack by the CeIV-bound hydroxide ion and that the reaction is further assisted by the general acid catalysis of another water bound to the CeIV ion.
|Number of pages||6|
|Journal||Journal of the Chemical Society, Perkin Transactions 2|
|Publication status||Published - 1995 Dec 1|
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