DIFFERENTIAL PATTERNS OF INTRACELLULAR METABOLISM OF 2',3'-DIDEHYDRO-2',3'-DIDEOXYTHYMIDINE AND 3'-AZIDO-2',3'-DIDEOXYTHYMIDINE, 2 POTENT ANTI-HUMAN IMMUNODEFICIENCY VIRUS COMPOUNDS

  • 15 April 1989
    • journal article
    • research article
    • Vol. 264  (11) , 6127-6133
Abstract
3''-Azido-2'',3''-dideoxythymidine (AZT) and 2'',3''-didehydro-2'',3''-dideoxythymidine (D4T) are potent and selective inhibitors of human immunodeficiency virus replication in MT-4 and ATH8 cells. They are also inhibitory to the replication of murine retroviruses, i.e. Moloney murine sarcoma virus-induced transformation of C3H cells. In MT-4 cells AZT is readily phosphorylated to its 5''-monophosphate, while the 5''-di- and 5''-triphosphates are generated to a 200-600 fold lower extent than the 5''-monophosphate. D4T is phosphorylated in MT-4 cells to its 5''-monophosphate at a 300-600-fold lower extent than AZT. The phosphorylation of AZT in the thymidine kinase-deficient cell line (Raji/TK-) is severely depressed, while D4T phosphorylation is only slightly diminished in Raji/TK- as compared to Raji/0 cells. D4T has a 10-fold lower affinity for phosphorylation by crude MT-4 cell extracts than AZT (Km, 142 and 14 .mu.M, respectively), and the Vmax for phosphorylation of D4T is only 5% that of AZT. D4T is phosphorylated by MT-4 cell extracts about 180-fold less efficiently than AZT (Vmax/Km, 0.06 for D4T, as compared to 11 for AZT), and this is consistent with the differences found in the amounts of phosphorylated products of D4T and AZT formed in intact MT-4 cells. The 5''-triphosphates of AZT and D4T are equipotent in their inhibitory effects on the reverse transcriptases from human immunodeficiency virus and Moloney murine leukemia virus.