Two derivatives of 5-deoxy-D-erythro-pent-4-enofuranose (4 and Gland 6-deoxy-alpha-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-alpha-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 x 10(-1) h(-1) at 50 degrees C, corresponding to a rate acceleration of about 10(3) as compared with that of the uncatalyzed reaction (9.1 x 10(-4) h(-1)). Competitive and noncompetitive inhibitions for this catalysis were observed on addition of sodium acetate (K-I = 5.9 x 10(-4) M) and K2HPO4 (K-I = 2.5 x 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 degrees C. The catalytic activity of the polymers seemed to be attributable to vic-cis-diol groups of furanose rings on the polymer backbones.