title: Selective inhibition of DNA polymerase alpha by a polysaccharide purified from slime of Physarum polycephalum.
abstract: A polysaccharide was purified from the slime of a myxomycete, Physarum polycephalum, and its inhibitory effect on eukaryotic DNA polymerases was examined. Almost all the calf thymus DNA polymerase alpha activity was inhibited with higher than 0.2 mg/ml of the polysaccharide, when the assay was carried out with activated DNA as a template. The inhibitory effect occurred regardless of the amounts of the enzyme and deoxyribonucleotides, however, kinetic analysis revealed that the inhibition occurs competitively with the template DNA, the Ki value being 4 micrograms/ml. Inhibition was observed for DNA polymerase alpha, but not for DNA polymerases beta and gamma from various eukaryote species.
mesh_terms: D000818:Animals; D002417:Cattle; D004257:DNA Polymerase II / Q000037:antagonists & inhibitors*; D007700:Kinetics; D010804:Physarum / Q000032:analysis*; D011134:Polysaccharides / Q000494:pharmacology*; D051381:Rats; D013950:Thymus Gland / Q000201:enzymology; D014981:Xenopus
chemical_list: D011134:Polysaccharides; D004257:DNA Polymerase II