Polymeric enzyme mimics: catalytic activity of ribose-containing polymers for a phosphate substrate

Abstract

The polymers containing ribose rings: poly(5′-acrylamido-5′-deoxy-1′,2′-O-isopropylidene-α-D-ribose) (11), poly(5′-acrylamido-5′-deoxy-α-D-ribose) (12) and poly(5′-acrylamido-5′-deoxy-1′-O-methyl-D-ribose) (13) were prepared as enzyme mimics. Polymers 12 and 13 with free vic-cis-diol groups catalyzed the hydrolysis of phosphodiester (ethyl p-nitrophenyl phosphate and N-methylpyridinium 4-tert-butylcatechol cyclic phosphate ) and phosphomonoester substrates with a rate acceleration of 10 ∼ 10³ compared with the uncatalyzed reaction. They also catalyzed the reverse reactions, i.e., the esterification of phosphomonoester to phosphodiester and the phosphorylation of alcohols with phosphate ions. The catalytic activity was attributable to the vic-cis-diols of riboses on polymer chains, which formed hydrogen bonds with two phosphoryl oxygen atoms of phosphates so as to activate the phosphorus atoms to be attacked by nucleophiles. The catalytic activity was negligible for polymer 11 where vic-cis-diol groups were blocked with isopropylidene groups. The catalytic activity was attributable to the vic-cis-diols of riboses on polymer chains, which formed hydrogen bonds with two phosphoryl oxygen atoms of phosphates so as to activate the phosphorus atoms to be attacked by nucleophiles.