Homogeneous catalyst for DNA hydrolysis (4). Efficient DNA hydrolysis by lanthanide--saccharide complexes

Homogeneous and neutral solutions are prepared by mixing Ce(NH4)2(NO3)6 with either isomaltose, melibiose, gentiobiose, palatinose, mannitol, sorbitol, galactitol, or glucamine in pH 7 hepes buffer (Ce(IV)]0/monomeric residue of saccharide]0 = 1). In contrast, amylose, cyclodextrins, maltose, glucose, and fructose provide only heterogeneous mixtures. The homogeneous solution of 1:1 Ce(IV)/glucamine system is active for DNA hydrolysis: the pseudo-first-order rate constant for the hydrolysis of thymidylyl(3'-->5')thymidine at pH 7.0 and 50 degrees C is 0.010 h-1, when Ce(IV)]0 = glucamine]0 = 10 mmol dm-3. The DNA-hydrolyzing activity decreases in the following order: glucamine > isomaltose, melibiose, gentiobiose > palatinose, mannitol, sorbitol, galactitol.