title: 5'-Amino-5'-deoxythymidine: synthesis, specific phosphorylation by herpesvirus thymidine kinase, and stability to pH of the enzymically formed diphosphate derivative.
abstract: Radioactive 5'-amino-5'-deoxythymidine (5'-AdThd), an inhibitor of herpes simplex virus, was synthesized by direct amination of monotosylated thymidine with concentrated ammonium hydroxide. Incubation of 5'-AdThd with purified herpes simplex virus type 1-encoded pyrimidine deoxyribonucleoside kinase produced the diphosphate derivative. The monphosphate derivative of 5'-AdThd was not detected as a reaction product of this enzymatic phosphorylation. A purified mixture of nonviral thymidine kinase and thymidylate kinase derived from uninfected Vero cells was unable to phosphorylate 5'-AdThd under identical conditions. The rate of hydrolysis of 5'-AdThd diphosphate increased as the pH of the reaction mixture decreased, with a shoulder region appearing between pH 3 and 5. The rate of hydrolysis was markedly increased below pH 3. 5'-AdThd, but not the monophosphate derivative, was detected in the hydrolysis mixture. The hydrolysis of 5'-AdThd diphosphate pH 3 also yielded some thymine in addition to 5'-AdThd.
mesh_terms: D015224:Dideoxynucleosides; D004355:Drug Stability; D006863:Hydrogen-Ion Concentration; D010766:Phosphorylation; D018139:Simplexvirus / Q000378:metabolism*; D013936:Thymidine / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000378:metabolism; D013937:Thymidine Kinase / Q000378:metabolism*
chemical_list: D015224:Dideoxynucleosides; C024082:5'-amino-5'-deoxythymidine; D013937:Thymidine Kinase; D013936:Thymidine