title: Effects of mercury (II) compounds on the activity of dUTPases from various sources.
abstract: The deoxyuridine triphosphate nucleotidohydrolases (dUTPases, EC 3.6.1.23) from Escherichia coli K-12-,Acholeplasma laidlawii B-PG9-, human KB cell-, and the herpes simplex virus (HSV) type 1- and 2-induced dUTPases were purified and used to determine the effect of various mercury (II) compounds on their activities. Mercuric acetate, 5-mercuri-dUTP (HgdUTP), and 5-mercuri-dCTP (HgdCTP) acted as irreversible active site-directed inhibitors of the dUTPases purified from eukaryotic organisms but not those from prokaryotic organisms. The inhibition constants (Ki) were estimated for the KB, HSV-1, and HSV-2 dUTPases to be 8 +/- 2, 12 +/- 3, and 9 +/- 2 microM for mercuric acetate, 204 +/- 25, 121 +/- 15, and 111 +/- 10 microM for HgdUTP, and 775 +/- 25 and 651 +/- 23 microM for HgdCTP, respectively. The conversion of HgdUTP to its mercurithio-derivative resulted in a decrease in the affinity of the derivative for the eukaryotic dUTPases. The 5-mercurithioethylene glycol derivative of dUTP did not act as a substrate for the KB dUTPase but it did act as a substrate for the HSV-1- and HSV-2-induced dUTPases with Ki values of 526 +/- 47 and 483 +/- 32 microM, respectively. These results demonstrate that the eukaryotic dUTPases can be distinguished based upon differences in their affinities for the mercurithio-derivatives of dUTP and suggest that there are differences in the steric binding properties of the nucleotide-binding site of these enzymes.
mesh_terms: D000128:Acholeplasma laidlawii / Q000201:enzymology; D000998:Antiviral Agents / Q000494:pharmacology; D001665:Binding Sites; D003845:Deoxycytosine Nucleotides / Q000494:pharmacology*; D003856:Deoxyuracil Nucleotides / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000201:enzymology; D006561:Herpes Simplex / Q000201:enzymology; D006801:Humans; D006868:Hydrolysis; D007624:KB Cells / Q000201:enzymology; D007700:Kinetics; D008623:Mercaptoethanol / Q000494:pharmacology; D008628:Mercury / Q000494:pharmacology*; D009941:Organomercury Compounds / Q000494:pharmacology*; D011755:Pyrophosphatases / Q000037:antagonists & inhibitors*; D013329:Structure-Activity Relationship; D013997:Time Factors
chemical_list: C037771:5-mercurideoxycytidine triphosphate; D000998:Antiviral Agents; D003845:Deoxycytosine Nucleotides; D003856:Deoxyuracil Nucleotides; D009941:Organomercury Compounds; D008623:Mercaptoethanol; C048410:5-mercurideoxyuridine triphosphate; D011755:Pyrophosphatases; C020020:dUTP pyrophosphatase; D008628:Mercury; C029823:mercuric acetate