FORMATION OF PHOSPHONESTER BONDS CATALYZED BY DNA-POLYMERASE

3'-Fluoro-2',3'-dideoxythymidine 5'-(alpha-methylphosphonyl)-beta, gamma- diphosphate and 2'-deoxythymidine-5' (alpha-methylphosphonyl)-beta,gamma- diphosphate have been synthesized. Both compounds are incorporated into DNA chains during catalysis by reverse transcriptases of human immunodeficiency (HIV) and avian myeloblastosis (AMV) viruses, DNA polymerase-beta from rat liver, terminal deoxynucleotidyl transferase from calf thymus and (at a very low rate) is by E.coli DNA polymerase I, Klenow fragment. The first compound is a termination substrate while the second is capable of multiple incorporation into the DNA chains. For instance, reverse transcriptase catalysis resulted in the appearance of 8 residues of second compound. DNA polymerases-alpha and epsilon from human placenta incorporated none of the above compounds into DNA chains, although an inhibition of DNA synthesis by both compounds was observed with all enzymes mentioned. The 3' --> 5'-exonuclease activity of DNA polymerase I, Klenow fragment, hydrolyzed DNA fragments containing phosphonomethyl internucleoside groups, while such DNA fragments were resistant to the E.coli exonuclease III.