Tramontano E, Cheng Y C
Department of Pharmacology, School of Medicine, Yale University, New Haven, CT 06510.
Biochem Pharmacol. 1992 Mar 17;43(6):1371-6. doi: 10.1016/0006-2952(92)90515-k.
The dipyridodiazepinone derivative 6,11-dihydro-11-cyclopropyl-4-methyldipyrido[2,3-b:2',3'-e]-[1,4] diazepin-6-one (BI-RG-587) selectively inhibits human immunodeficiency virus type 1 (HIV-1) replication by suppressing HIV-1 reverse transcriptase activity. Both RNA- and DNA-dependent polymerase associated activities of this enzyme were found to be inhibited by BI-RG-587 in a pattern dependent on the template used. The lowest IC50 values were obtained using poly(rC)-oligo(dG)12-18 and poly(dA)-oligo(dT)12-18 as template-primer. For the RNA-dependent activity poly(rC)-oligo(dG)12-18 and dGTP appeared to enhance the inhibition of the RNA-dependent enzyme activity by BI-RG-587, with the effect of poly(rC)-oligo(dG)12-18 dominating that of dGTP. Poly(rA)-oligo(dT)10 seemed to decrease the inhibition whereas poly(rU)-oligo(dA)12-18 or poly(rG)-oligo-(dC)12-18 had no effect. dATP, dTTP and dCTP, three nucleotide triphosphates, also had no impact on the inhibition. Differences were observed for the template-dependent action of BI-RG-587 against the DNA-dependent enzyme activity. Both substrates were required to allow the inhibition by BI-RG-587 in the poly(dC)-oligo(dG)12-18 and dGTP reaction, whereas only the template and enzyme interaction seemed to be necessary for the poly(dA)-oligo(dT)12-18 and dTTP reaction. The different behaviors of DNA- and RNA-dependent DNA polymerase activities could indicate either the presence of different active sites for distinct activities or the presence of a unique active site with different configurations depending upon the template used. Also, BI-RG-587 showed a mutually exclusive inhibition when combined with two other classes of HIV-1 RT inhibitors represented by phosphonoformic acid and 3'-azido-3'-dideoxythymidine triphosphate.
二吡啶并二氮杂卓酮衍生物6,11-二氢-11-环丙基-4-甲基二吡啶并[2,3-b:2',3'-e]-[1,4]二氮杂卓-6-酮（BI-RG-587）通过抑制HIV-1逆转录酶活性来选择性抑制1型人类免疫缺陷病毒（HIV-1）复制。发现该酶的RNA依赖性和DNA依赖性聚合酶相关活性均被BI-RG-587以依赖于所用模板的方式抑制。使用聚（rC）-寡聚（dG）12-18和聚（dA）-寡聚（dT）12-18作为模板引物时获得最低IC50值。对于RNA依赖性活性，聚（rC）-寡聚（dG）12-18和dGTP似乎增强了BI-RG-587对RNA依赖性酶活性的抑制作用，聚（rC）-寡聚（dG）12-18的作用主导了dGTP的作用。聚（rA）-寡聚（dT）10似乎降低了抑制作用，而聚（rU）-寡聚（dA）12-18或聚（rG）-寡聚（dC）12-18则无作用。三磷酸核苷酸dATP、dTTP和dCTP对抑制作用也无影响。观察到BI-RG-587对DNA依赖性酶活性的模板依赖性作用存在差异。在聚（dC）-寡聚（dG）12-18和dGTP反应中，两种底物均需存在才能使BI-RG-587产生抑制作用，而在聚（dA）-寡聚（dT）12-18和dTTP反应中，似乎仅模板与酶的相互作用是必需的。DNA依赖性和RNA依赖性DNA聚合酶活性的不同行为可能表明存在针对不同活性的不同活性位点，或者存在取决于所用模板的具有不同构象的独特活性位点。此外，当BI-RG-587与另外两类以膦甲酸和3'-叠氮-3'-脱氧胸苷三磷酸为代表的HIV-1逆转录酶抑制剂联合使用时，表现出相互排斥的抑制作用。
