The mode of inhibitory action by pyridoxal 5-phosphate on DNA polymerase-α and -β

• Published in: Nucleic acids research Vol. 7; no. 3; pp. 727 - 734
• Main Authors: Oguro, Mieko, Nagano, Hiroshi, Mano, Yoshitake
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 10.10.1979
• Subjects: Animals; Binding, Competitive; DNA Polymerase I - antagonists & inhibitors; DNA Polymerase II - antagonists & inhibitors; Echinoidea; Embryo, Nonmammalian - enzymology; Female; Kinetics; Nucleic Acid Synthesis Inhibitors; Pyridoxal Phosphate - analogs & derivatives; Pyridoxal Phosphate - pharmacology; Sea Urchins - enzymology; Structure-Activity Relationship
• ISSN: 0305-1048; 1362-4962
• DOI: 10.1093/nar/7.3.727

The kinetics of the inhibition of DNA polymerases-α and -β from sea urchin embryos by pyridoxal 5-phosphate were studied. The inhibition of DNA polymerase-α activity by pyridoxal 5-phosphate was competitive with activated DNA but noncompetitive with each deoxynucleoside triphosphate. With poly(dC)-oligo(dG)12–18 as a template-primer, however, the inhibition of DNA polymerase-α was competitive with dGTP but noncompetitive with the template-primer. These results suggest that DNA polymerase-α interacts with activated DNA and poly(dC)-oligo(dG)12–18 in different ways. The inhibition of DNA polymerase-β by pyridoxal 5-phosphate was competitive with deoxynucleoside triphosphate using activated DNA as a template-primer and noncompetitive with activated DNA. Using poly(rA)-oligo(dT)12–18 as a template-primer, DNA polymerase-β activity yielded sigmoid curves against both dTTP and the template-primer concentrations and was inhibited by pyridoxal 5-phosphate noncompetitively with respect to both dTTP and the template-primer. These results indicate that the inhibitory mode of DNA polymerase-α by pyridoxal 5-phosphate is different from that of DNA polymerase-β.