9-Beta-D-arabinofuranosyladenine 5'-monophosphate (araAMP) is converted directly to its antivirally active 5'-triphosphate form by 5-phosphoribosyl-1-pyrophosphate (PRPP) synthetase

Biochem Biophys Res Commun. 1990 Dec 31;173(3):781-7. doi: 10.1016/s0006-291x(05)80855-1.


The antiherpetic agent 9-beta-D-arabinofuranosyladenine (araA) needs to be phosphorylated to its 5'-triphosphate to be effective as an inhibitor of herpes simplex virus replication. Adenosine kinase and deoxycytidine kinase are assumed to convert araA to its 5'-monophosphate. We now found that araAMP is converted to its 5'-triphosphate through a direct pyrophosphate transfer from 5-phosphoribosyl-1-pyrophosphate (PRPP) by PRPP synthetase. The efficiency of phosphorylation of araAMP to araATP is about 5% of that of AMP, as estimated from their Vmax/Km ratios for PRPP synthetase. AraATP is converted to araAMP by PRPP synthetase at a 4-fold higher Km but similar Vmax as ATP.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Kinetics
  • Ribose-Phosphate Pyrophosphokinase / metabolism*
  • Vidarabine Phosphate / analogs & derivatives*
  • Vidarabine Phosphate / metabolism*


  • Vidarabine Phosphate
  • ara-ATP
  • Ribose-Phosphate Pyrophosphokinase