title: Protection of vaccinia from heat inactivation by nucleotide triphosphates.
abstract: The presence of adenosine triphosphate, guanosine triphosphate, cytosine triphosphate, or uridine triphosphate reduced the rate of inactivation of vaccinia when heated at 50 C. The virus-associated nucleoside triphosphate phosphohydrolases (adenosine triphosphatase, guanosine triphosphatase, cytosine triphosphatase, and uridine triphosphatase) and ribonucleic acid polymerase were also protected from heat inactivation by these compounds. These obervations are best explained by postulating that ribonucleoside triphosphates bind to enzymes in the virus particle, and that these enzyme-substrate complexes are more resistant to thermal denaturation than are the enzymes without their substrates. The kinetics of heat inactivation of the vaccinia ATP phosphohydrolase activity is biphasic, suggesting that there are two proteins in the vaccinia particle that have this enzyme activity but they have different kinetics of heat inactivation. Any of the vaccinia-associated nucleotide phosphohydrolase activities are protected from heat inactivation by the presence of any one of the respective nucleoside triphosphates. This observation suggests that there is a single enzymatic site in vaccinia that is able to react with any ribonucleoside triphosphate.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000596:Amino Acids; D002247:Carbon Isotopes; D002460:Cell Line; D002499:Centrifugation, Density Gradient; D003597:Cytosine Nucleotides / Q000494:pharmacology*; D006150:Guanine Nucleotides / Q000494:pharmacology*; D006358:Hot Temperature; D008854:Microscopy, Electron; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D012316:RNA Nucleotidyltransferases / Q000378:metabolism; D013395:Sucrose; D013501:Surface-Active Agents; D014500:Uracil Nucleotides / Q000494:pharmacology*; D014616:Vaccinia virus / Q000032:analysis / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development / Q000302:isolation & purification / Q000472:pathogenicity*; D014764:Viral Proteins / Q000032:analysis
chemical_list: D000596:Amino Acids; D002247:Carbon Isotopes; D003597:Cytosine Nucleotides; D006150:Guanine Nucleotides; D013501:Surface-Active Agents; D014500:Uracil Nucleotides; D014764:Viral Proteins; D013395:Sucrose; D000255:Adenosine Triphosphate; D012316:RNA Nucleotidyltransferases; D010744:Phosphoric Monoester Hydrolases; D000251:Adenosine Triphosphatases