KINETIC-ANALYSIS OF THE INTERACTION OF CIDOFOVIR DIPHOSPHATE WITH HUMAN CYTOMEGALOVIRUS DNA-POLYMERASE

Cidofovir [CDV, )-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine, HPM PC] is an acyclic cytosine nucleoside phosphonate analog with potent i n vitro and in vivo activity against a broad spectrum of herpesviruses . CDV diphosphate (CDVpp), the putative antiviral metabolite of CDV, i s a competitive inhibitor of dCTP and an alternate substrate for human cytomegalovirus (HCMV) DNA polymerase. HCMV DNA polymerase used a syn thetic DNA primer-template with a K-m value of 90 +/- 8 nM and incorpo rated dCTP approximately 42 times more efficiently than CDVpp. HCMV DN A polymerase also utilized a synthetic DNA primer containing a single molecule of CDV at the 3'-terminus. The K-m value for this DNA primer- template was 165 +/- 42 nM and incorporation of dCTP was approximately 17 times more efficient than that of CDVpp. The slower rate of incorp oration of CDVpp was due mostly to the higher K-m value of CDVpp towar d the enzyme-primer-template complexes. These data demonstrate that in corporation of a single CDV into DNA by HCMV DNA polymerase does not l ead to chain termination.