Iwanami O N, Shudo K, Hashimoto Y
Faculty of Pharmaceutical Sciences, University of Tokyo, Japan.
Nucleic Acids Symp Ser. 1993(29):15-6.
Meso-DNAs, containing L-sugar and D-sugar in an alternate sequence as the backbone [Fig. 1, designated as LD-(dN)n], were prepared as a modificated oligonucleotides of natural- and enantio-DNA. The characteristics of meso-DNAs were analyzed, focusing on LD-(dA)n and LD-(dT)n. These L-sugar containing oligomers show resistancy to phosphodiesterases. Though both LD-(dA)n and LD-(dT)n bound their corresponding complementary homopolymers, apparent differences of the interaction mode between these two meso-DNAs were observed: [1] Concerning the complex formation with the complementary homopolymers, LD-(dA)n favors a triplex formation while LD-(dT)n forms only duplex, and [2] Concerning DNA/RNA selectivity for the complex formation, LD-(dA)n interacted with poly U more strongly than poly dT (RNA-selective), while LD-(dT)n showed stronger interaction with poly dA than poly A (DNA-selective). The similarities in CD-spectra of LD-oligomer/natural polymer complexes to natural complexes suggest that the conformation possesses a structure close to a natural right-handed helix conformation.
中-DNA（Meso-DNAs）是一种修饰的天然DNA和对映体DNA寡核苷酸，其骨架中L-糖和D-糖交替排列[图1，标记为LD-(dN)n]。对中-DNA的特性进行了分析，重点研究了LD-(dA)n和LD-(dT)n。这些含L-糖的寡聚物对磷酸二酯酶具有抗性。尽管LD-(dA)n和LD-(dT)n都能与它们相应的互补同聚物结合，但观察到这两种中-DNA之间相互作用模式存在明显差异：[1]关于与互补同聚物形成复合物，LD-(dA)n倾向于形成三链体，而LD-(dT)n仅形成双链体；[2]关于复合物形成的DNA/RNA选择性，LD-(dA)n与聚U的相互作用比聚dT更强（RNA选择性），而LD-(dT)n与聚dA的相互作用比聚A更强（DNA选择性）。LD-寡聚物/天然聚合物复合物的圆二色光谱（CD-spectra）与天然复合物的相似性表明，其构象具有接近天然右手螺旋构象的结构。
