Kim H K, Kim J M, Kim S K, Rodger A, Nordén B
Department of Chemistry, College of Sciences, Yeungnam University, Kyoungsan City, Kyoung-buk, Republic of Korea.
Biochemistry. 1996 Jan 30;35(4):1187-94. doi: 10.1021/bi951913m.
The binding of 9-aminoacridine and one bis-acridine compound to double helical poly(dA).poly-(dT) and poly[d(A-T)]2 and triple helical poly(dA).[poly(dT)]2 has been investigated using linear dichroism (LD) and circular dichroism (CD). A close examination of the negative reduced LD and the induced CD for the first pi-->pi* transition absorption region leads us to conclude that the acridine moiety of the 9-aminoacridine and bis-acridine molecule intercalates with both duplex and triplex DNA. Binding geometries of the acridine moieties in the examined polynucleotides are similar to those found for the ligands with DNA (Hansen et al. (1984) J. Chem. Soc., Chem. Commun., 509-511). It is also found that both 9-aminoacridine and bis-acridine effectively enhance the thermal stability of the triplex DNA. The corresponding spectra for the complexes of the minor groove binders DAPI and Hoechst with poly-(dA).[poly(dT)]2 were studied for comparison. They both show a positive LD and a mixing ratio dependent positive CD in the ligand absorption region, similar to those of their duplex complexes. This indicates that these ligands bind in the grooves of the triplex, probably to the one corresponding to the minor groove of the template duplex.
利用线性二色性（LD）和圆二色性（CD）研究了9-氨基吖啶和一种双吖啶化合物与双螺旋聚（dA）·聚（dT）、聚[d（A-T）]2以及三螺旋聚（dA）·[聚（dT）]2的结合情况。对第一个π→π*跃迁吸收区域的负还原LD和诱导CD进行仔细研究后，我们得出结论：9-氨基吖啶和双吖啶分子的吖啶部分与双链和三链DNA均发生嵌入作用。在所研究的多核苷酸中，吖啶部分的结合几何结构与那些与DNA结合的配体所发现的结构相似（Hansen等人，（1984年）《化学学会杂志，化学通讯》，509 - 511页）。还发现9-氨基吖啶和双吖啶均能有效提高三链DNA的热稳定性。为作比较，研究了小沟结合剂DAPI和Hoechst与聚（dA）·[聚（dT）]2形成的复合物的相应光谱。它们在配体吸收区域均显示出正LD和依赖混合比的正CD，类似于它们与双链形成的复合物。这表明这些配体结合在三链的沟中，可能是结合在与模板双链小沟相对应的那个沟中。
