Broyde S, Hingerty B
Chem Biol Interact. 1983 Oct 15;47(1):69-78. doi: 10.1016/0009-2797(83)90148-5.
Minimized conformational potential energy calculations have been performed for the 7-iodo (AAIF) and 7-fluoro (AAFF) derivatives of N-2-acetylaminofluorene (AAF), linked covalently to guanine C-8 in dCpdG. Both the iodo and the fluoro derivatives are carcinogenic and mutagenic. The lowest energy forms on the dinucleoside monophosphate level have syn guanine and fluorene-cytidine stacking. However, the iodo adduct cannot adopt this conformation in larger polymers, according to earlier experimental studies (Fuchs et al., Biochemistry, 15 (1976) 3347) and model building, because of iodine's large Van der Waal's radius. Therefore, a model consistent with all the experimental evidence, incorporating the second lowest energy conformation in B form duplex (dCdG)3 was constructed. In this model the modified guanine is syn, yet still stacked with the adjacent cytidine in one direction, the fluorene is located primarily at the helix interior between the base pairing sites, rupturing two base pairs, and the iodine atom and its adjoining ring protrude to the helix exterior.
已对N - 2 - 乙酰氨基芴（AAF）的7 - 碘代（AAIF）和7 - 氟代（AAFF）衍生物进行了最小化构象势能计算，这些衍生物与dCpdG中的鸟嘌呤C - 8共价连接。碘代和氟代衍生物均具有致癌性和致突变性。在单磷酸二核苷水平上，能量最低的形式具有顺式鸟嘌呤和芴 - 胞苷堆积。然而，根据早期的实验研究（Fuchs等人，《生物化学》，15（1976）3347）和模型构建，由于碘的范德华半径较大，碘代加合物在更大的聚合物中无法采用这种构象。因此，构建了一个与所有实验证据一致的模型，该模型纳入了B型双链体（dCdG）3中能量第二低的构象。在这个模型中，修饰的鸟嘌呤是顺式的，但仍在一个方向上与相邻的胞苷堆积，芴主要位于碱基配对位点之间的螺旋内部，破坏了两个碱基对，碘原子及其相邻环向螺旋外部突出。
