Synthesis of the polysaccharide, (1→5)-α-D-ribofuranan and its catalytic activities for the hydrolysis of phosphates and the cleavage of nucleic acids

Abstract

The polysaccharide, (1ç5)-α-D-ribofuranan, was synthesized by a cationic ring-opening polymerization of 1,4-anhydro-2,3-di-O-benzyl-α-D-ribopyranose with the aid of boron trifluoride etherate and subsequent debenzylation. This polysaccharide catalyzed the hydrolysis of ethyl p-nitrophenyl phosphate, uridylyl(3´ç5´)uridine ammonium salt, and 4-tert-butylcatechol cyclic phosphate N-methyl pyridinium. The polymer also catalyzed the cleavage of nucleic acids (DNA and RNA). The hydrolysis of ethyl p-nitrophenyl phosphate in the presence of the polymer was accelerated by 1.5Ý 10 3 times relative to the uncatalyzed reaction. The catalytic activity was attributable to the vic-cis-diols of the riboses being located inside the active center that is formed by polymer chain folding; these diols form hydrogen bonds with two phosphoryl oxygen atoms of the phosphates so as to activate the phosphorus atoms to be attacked by nucleophile (H 2 O).