title: Pyridoxal 5'-phosphate inhibition of adenovirus DNA polymerase.
abstract: Pyridoxal phosphate modification of adenovirus DNA polymerase results in loss of DNA polymerase activity, whereas the 3' --> 5' exonuclease activity is unaffected. Inhibition by pyridoxal phosphate is time-dependent, displays saturation kinetics, and is reversible in the presence of excess primary amine unless the pyridoxal phosphate-enzyme adduct is first reduced with NaBH4. Thus, inhibition is the consequence of Schiff base formation between the aldehyde moiety of pyridoxal phosphate and primary amino groups on the enzyme. In addition to inhibiting DNA polymerase activity, pyridoxal phosphate also inhibited the ability of the enzyme to initiate viral DNA replication, by transfer of dCMP onto the preterminal protein. Neither template-primer nor dNTP protect against pyridoxal phosphate inhibition, but the combination of template-primer and complementary substrate dNTP protected both initiation and DNA polymerase activities. Thus, it is likely that both the dCMP transfer activity required for initiation and DNA polymerase activity are carried out at the same site of the enzyme.
authors.affiliation: School of Biological and Medical Sciences, Irvine Building, University of St. Andrews, Fife KY16 9AL, Scotland, United Kingdom.
authors.forename: A
authors.initials: A
authors.lastname: Monaghan
authors.forename: R T
authors.initials: RT
authors.lastname: Hay
mesh_terms: D000256:Adenoviridae / Q000201:enzymology*; D000818:Animals; D003843:Deoxycytidine Monophosphate / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005092:Exonucleases / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D019384:Nucleic Acid Synthesis Inhibitors; D017924:Nucleopolyhedroviruses; D010750:Phosphoproteins / Q000378:metabolism; D011498:Protein Precursors / Q000378:metabolism; D011732:Pyridoxal Phosphate / Q000378:metabolism / Q000494:pharmacology*; D011994:Recombinant Proteins; D018411:Spodoptera; D014764:Viral Proteins; D014779:Virus Replication
chemical_list: D004791:Enzyme Inhibitors; D019384:Nucleic Acid Synthesis Inhibitors; D010750:Phosphoproteins; D011498:Protein Precursors; D011994:Recombinant Proteins; D014764:Viral Proteins; C085476:pTP protein, adenovirus; D003843:Deoxycytidine Monophosphate; D011732:Pyridoxal Phosphate; D005092:Exonucleases