Initeractions of Glycosaminoglycans with DNA and RNA Synthesizing Enzymes in vitro

Abstract

The sulfated glycosaminoglycans chondroitin 4-sulfate, chondroitin 6-sulfate, keratan sulfate, dermatan sulfate, heparin and a glycosaminoglycan polysulfate are competitive inhibitors of [Escherichia coli] DNA-dependent DNA polymerase, DNA-dependent RNA polymerase and avian myeloblastosis virus RNA-dependent DNA polymerase (reverse transcriptase). The unsulfated glycosaminoglycans chondroitin and hyaluronate do not affect DNA and RNA synthesis. The strongest inhibitor is a glycosaminoglycan polysulfate with 4 sulfate groups/disaccharide unit. It has the following inhibitor constants: DNA polymerase, Ki = 1.5 .times. 10-6 M; RNA polymerase, Ki = 0.9 .times. 10-6 M; reverse transcriptase, Ki = 1.1 .times. 10-6 M. The inhibition is closely correlated to the degree of sulfation of the glycosaminoglycans. There is a relationship between the sulfate/hexosamine ratio and the degree of inhibition. Inhibition of the DNA and RNA synthesizing enzymes by sulfated glycosaminoglycans depends on the nature of the template. With double-stranded DNA as template, inhibition occurs only when sulfated glycosaminoglycans are added before or shortly after (30 s) initiation of the synthesis. There is no inhibition if the inhibitors are added after the onset of the synthesis. With a single-stranded template, synthesis was blocked completely at each phase of reaction.