Interactions of glycosaminoglycans with DNA and RNA synthesizing enzymes in vitro.

The sulfated glycosaminoglycans chondroitin 4-sulfate, chondroitin 6-sulfate, keratan sulfate, dermatan sulfate, heparin, and glycosaminoglycan polysulfate are competitive inhibitors of the DNA-dependent RNA polymerase, the DNA-dependent RNA polymerase and the RNA-dependent DNA polymerase (reverse transcriptase). The unsulfated glycosaminoglycans chondroitin and hyaluronate are without any influence on the synthesis of DNA and RNA. The strongest inhibitor is a glycosaminoglycan polysulfate with four sulfate groups per disaccharide unit. It has the following inhibitor constants: DNA polymerase, Ki = 1.5 X 10(-6) M; RNA polymerase, Ki = 0.9 X 10(-6) M; reverse transcriptase, Ki = 1.1 X 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. The 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. On the other hand, with a single-stranded template synthesis was blocked completely at each phase of reaction.