title: The mode of inhibitory action by pyridoxal 5-phosphate on DNA polymerase-alpha and -beta.
abstract: The kinetics of the inhibition of DNA polymerases-alpha and -beta from sea urchin embryos by pyridoxal 5-phosphate were studied. The inhibition of DNA polymerase-alpha 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-alpha was competitive with dGTP but noncompetitive with the template-primer. These results suggest that DNA polymerase-alpha interacts with activated DNA and poly(dC)-oligo(dG)12-18 in different ways. The inhibition of DNA polymerase-beta 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-beta 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-alpha by pyridoxal 5-phosphate is different from that of DNA polymerase-beta.
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D004256:DNA Polymerase I / Q000037:antagonists & inhibitors*; D004257:DNA Polymerase II / Q000037:antagonists & inhibitors*; D004625:Embryo, Nonmammalian / Q000201:enzymology; D005260:Female; D007700:Kinetics; D019384:Nucleic Acid Synthesis Inhibitors; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives / Q000494:pharmacology*; D012617:Sea Urchins / Q000201:enzymology; D013329:Structure-Activity Relationship
chemical_list: D019384:Nucleic Acid Synthesis Inhibitors; D011732:Pyridoxal Phosphate; D004256:DNA Polymerase I; D004257:DNA Polymerase II