Reardon J E, Crouch R C, St John-Williams L
Division of Experimental Therapy, Wellcome Research Laboratories, Research Triangle Park, North Carolina 27709.
J Biol Chem. 1994 Jun 10;269(23):15999-6008.
3'-Azido-3'-deoxythymidine (AZT), AZT 5'-monophosphate, and AZT 5'-triphosphate (AZTTP) were reduced by dithiothreitol with second-order rate constants of 2.30 x 10(-3), 1.50 x 10(-3), and 7.46 x 10(-4) M-1 s-1, respectively. Handlon and Oppenheimer reported that AZT is quantitatively reduced by thiols to 3'-amino-3'-deoxythymidine (Handlon, A. L., and Oppenheimer, N. J. (1988) Pharm. Res. (N.Y.) 5, 297-299). In the present report, multiple products of this reaction were identified by the techniques of UV spectroscopy, phosphate analysis, coelution with authentic standards from reversed-phase high pressure liquid chromatography, two-dimensional NMR spectroscopy, and mass spectrometry. The product mixture from reduction of AZT 5'-monophosphate at pH 7.1 and 25 degrees C was composed of 2,3'-anhydro-beta-D-threo-thymidine 5'-monophosphate (6.4%), 3'-amino-3'-deoxythymidine 5'-monophosphate (19.6%), beta-D-threo-thymidine 5'-monophosphate (6.8%), thymine and 3-amino-2,3-dideoxyribal 5-monophosphate (8.9%), beta-D-threo-thymidine 3',5'-cyclic monophosphate (9.1%), 3'-deoxy-2',3'-didehydrothymidine 5'-monophosphate (31.5%), and 3',5'-anhydro-beta-D-threo-thymidine (17.8%). Thymine and 3',5'-anhydro-beta-D-threo-thymidine were also products of reduction of AZT and AZTTP. Furthermore, the nucleosides of the above monophosphates were products of reduction of AZT, and the corresponding triphosphates were products of reduction of AZTTP. The product ratios were dependent on the level of phosphorylation of AZT and on the pH of the reaction. Mechanisms for formation of these products are proposed.
3'-叠氮-3'-脱氧胸苷（AZT）、5'-单磷酸AZT和5'-三磷酸AZT（AZTTP）可被二硫苏糖醇还原，其二级反应速率常数分别为2.30×10⁻³、1.50×10⁻³和7.46×10⁻⁴ M⁻¹ s⁻¹。汉德伦和奥本海默报告称，AZT可被硫醇定量还原为3'-氨基-3'-脱氧胸苷（汉德伦，A.L.，和奥本海默，N.J.（1988年）《药物研究》（纽约）5，297 - 299）。在本报告中，通过紫外光谱、磷酸盐分析、与反相高压液相色谱中的标准品共洗脱、二维核磁共振光谱和质谱等技术鉴定了该反应的多种产物。在pH 7.1和25℃条件下，5'-单磷酸AZT还原反应的产物混合物由2,3'-脱水-β-D-苏式胸苷5'-单磷酸（6.4%）、3'-氨基-3'-脱氧胸苷5'-单磷酸（19.6%）、β-D-苏式胸苷5'-单磷酸（6.8%）、胸腺嘧啶和3-氨基-2,3-二脱氧核糖醛5-单磷酸（8.9%）、β-D-苏式胸苷3',5'-环单磷酸（9.1%）、3'-脱氧-2',3'-二脱氢胸苷5'-单磷酸（31.5%）和3',5'-脱水-β-D-苏式胸苷（17.8%）组成。胸腺嘧啶和3',5'-脱水-β-D-苏式胸苷也是AZT和AZTTP还原反应的产物。此外，上述单磷酸的核苷是AZT还原反应的产物，相应的三磷酸是AZTTP还原反应的产物。产物比例取决于AZT的磷酸化水平和反应的pH值。文中提出了这些产物的形成机制。
