Abstract
A DNA polymerase β (pol. β) inhibitor has been isolated independently from two organisms; a red perilla, Perilla frutescens, and a mugwort, Artemisia vulgaris. These molecules were determined by spectroscopic analyses to be the cyanogenic glucoside, D-mandelonitrile-β-D-glucoside, prunasin. The compound inhibited the activity of rat pol. β at 150 μM, but did not influence the activities of calf DNA polymerase α and plant DNA polymerases, human immunodefficiency virus type 1 reverse transcriptase, calf terminal deoxynucleotidyl transferase, or any prokaryotic DNA polymerases, or DNA and RNA metabolic enzymes examined. The compound dose-dependently inhibited pol. β activity, the IC50, value being 98 μM with poly dA/oligo dT12-18 and dTTP as the DNA template and substrate, respectively. Inhibition of pol. β by the compound was competitive with the substrate, dTTP. The inhibition was enhanced in the presence of fatty acid, and the IC50 value decreased to approximately 40 μM. In the presenceof C10-decanoic acid, the K1 value for substrate dTTP decreased by 28-fold, suggesting that the fatty acid allowed easier access of the compound to the substrate-binding site.
