Ribofuranose-Containing Polymers:  Synthesis and Catalytic Activity for the Hydrolysis of Phosphodiester and the Cleavage of DNA

Two derivatives of 5-deoxy-d-erythro-pent-4-enofuranose (4 and 6) and 6-deoxy-α-d-galacto-hex-5-enopyranose (9) were synthesized. Copolymerization of these monomers with maleic anhydride and subsequent reactions resulted in poly[(5-deoxy-d-erythro-pent-4-enofuranose)-alt-(maleic acid)] (11) and its derivatives, such as dimethyl ester (12), 2,3-O-isopropylidene (13), 1-O-methyl (15), and poly[(6-deoxy-α-d-galacto-hex-5-enopyranose)-alt-(maleic acid)] (17). Polymers 11, 12, and 15 showed catalytic activity for the hydrolysis of phosphodiesters. The rate constant (k cat) for the hydrolysis of ethyl p-nitrophenyl phosphate substrate catalyzed by polymer 12 was 9.0 × 10-1 h-1 at 50 °C, corresponding to a rate acceleration of about 103 as compared with that of the uncatalyzed reaction (9.1 × 10-4 h-1). Competitive and noncompetitive inhibitions for this catalysis were observed on addition of sodium acetate (K I = 5.9 × 10-4 M) and K2HPO4 (K I = 2.5 × 10-4 M), respectively. The polymers also catalyzed the cleavage of ssDNA of 30 bases and tetradeoxyadenylic acid in Tris buffer (pH 7.4) at ionic strength 0.02 (KCl) at 37 °C. The catalytic activity of the polymers seemed to be attributable to vic-cis-diol groups of furanose rings on the polymer backbones.