Adenosine- and ADP-phosphorylating capacity of herpes simplex virus-induced thymidine kinase enzyme complex

The herpes simplex virus(HSV)-coded thymidine kinase (TK) enzyme complex was isolated from HSV type 1 strain Lennette(TK+)-infected CLID (TK-) cells and was enriched by streptomycin sulfate and ammonium sulfate fractionation. This enzyme preparation was tested for dTMP:Ado (adenosine) and for dTMP:ADP phosphotransferase activities. The presence of dTMP:Ado phosphotransferase activity was proven by time-course studies with cells infected for 0-18 h, by biophysical studies in polyacrylamide gels, by affinity chromatography studies using AMP- and dTMP-Sepharose, and by immuno-neutralization experiments. The presence of dTMP:ADP phosphotransferase activity was demonstrated by kinetic experiments. These results were taken as evidence that the two functional subunits of the HSV-TK enzyme complex, AMP:dThd (deoxythymidine) phosphotransferase and ATP: dThd kinase, catalyze highly reversible enzyme reactions. New data are presented indicating that the ATP:dThd kinase is a nonspecific enzyme with respect to the nucleoside acceptor.