Selective inhibition of DNA polymerase alpha by a polysaccharide purified from slime of Physarum polycephalum

Biochem Biophys Res Commun. 1987 Jul 15;146(1):61-6. doi: 10.1016/0006-291x(87)90690-5.


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

  • Animals
  • Cattle
  • DNA Polymerase II / antagonists & inhibitors*
  • Kinetics
  • Physarum / analysis*
  • Polysaccharides / pharmacology*
  • Rats
  • Thymus Gland / enzymology
  • Xenopus


  • Polysaccharides
  • DNA Polymerase II