KINETIC INTERACTION OF THE DIPHOSPHATES OF 9-(2-PHOSPHONYLMETHOXYETHYL)ADENINE AND OTHER ANTI-HIV ACTIVE PURINE CONGENERS WITH HIV REVERSE-TRANSCRIPTASE AND HUMAN DNA POLYMERASE-ALPHA, POLYMERASE-BETA AND POLYMERASE-GAMMA

The inhibitory effects of the diphosphates of 9-(2-phosphonylmethoxyet hyl)adenine (PMEA) and its analogues on HIV reverse transcriptase and human DNA polymerases alpha, beta, and gamma have been studied. The an alogues investigated are the diphosphates of 9-(2-phosphonylmethoxypro pyl)adenine (PMPApp), 9-(2-phosphonylmethoxypropyl)-2,6-diaminopurine (PMPDAPpp), and (2R,5R)-9-[2,5-dihydro-5-(phosphonyl methoxy)-2-furany l]adenine (D4APpp). These four compounds are much more inhibitory to H IV reverse transcriptase when an RNA template rather than a DNA templa te is used. The K-i values for the four compounds range from 11 to 22 nM with an RNA template. The K-i values for ddCTP and AZTTP are 54 nM and 8 nM, respectively. PMEApp and its analogues show varying degrees of inhibition of the human DNA polymerases, The K-i values for pMEApp, PMPApp and PMPDAPpp against DNA polymerase alpha are in the micromola r range, while D4APpp is a poor inhibitor of this enzyme with a K-i va lue of 65.9 mu M. The inhibition of DNA polymerase beta by PMEApp, PMP App and D4APpp is minimal, while PMPDAPpp shows higher inhibition of D NA polymerase beta with a K-i value of 9.71 mu M. The K-i values for P MEApp and D4APpp against DNA polymerase gamma are submicromolar while PMPApp and PMPDAPpp are much less inhibitory to this enzyme. For compa rison, ddCTP was found to be a more potent inhibitor of DNA polymerase s beta and gamma than the diphosphates of PMEA and its analogues.