Uesugi S, Lee B L, Ikehara M, Fujii S, Tomita K
Faculty of Pharmaceutical Sciences, Osaka University, Japan.
Biochemistry. 1988 Jan 26;27(2):521-5. doi: 10.1021/bi00402a002.
It is known that oligonucleotides containing cyclonucleosides with a high anti (intermediate between anti and syn) glycosidic conformation adopt left-handed, single- and double-helical structures [Uesugi, S., Yano, J., Yano, E., & Ikehara, M. (1977) J. Am. Chem. Soc. 99, 2313-2323]. In order to see whether DNA can adopt the high anti left-handed double-helical structure or not, a self-complementary hexanucleotide containing 6,2'-O-cyclocytidine (C(o)), 8,2'-O-cycloguanosine (G(o)), thymidine, and deoxyadenosine, C(o)G(o)dTdAC(o)G(o), was synthesized. Imino proton NMR spectra and the results of nuclear Overhauser effect experiments strongly suggest that C(o)G(o)dTdAC(o)G(o) adopts a left-handed double-helical structure where the deoxynucleoside residues are involved in hydrogen bonding and take a high anti glycosidic conformation. A conformational model of the left-handed duplex was obtained by calculation with energy minimization. Thus it appears that DNA can form a high anti, left-handed double helix under some constrained conditions, which is quite different from that of Z-DNA.
已知含有具有高反式（介于反式和顺式之间）糖苷构象的环核苷的寡核苷酸会形成左手单螺旋和双螺旋结构[上杉，S.，矢野，J.，矢野，E.，&池原，M.（1977年）《美国化学会志》99，2313 - 2323]。为了探究DNA是否能形成高反式左手双螺旋结构，合成了一种自互补六核苷酸，其包含6,2'-O-环胞苷（C(o)）、8,2'-O-环鸟苷（G(o)）、胸腺嘧啶核苷和脱氧腺苷，即C(o)G(o)dTdAC(o)G(o)。亚氨基质子核磁共振谱以及核Overhauser效应实验结果有力地表明，C(o)G(o)dTdAC(o)G(o)形成了一种左手双螺旋结构，其中脱氧核苷残基参与氢键形成并具有高反式糖苷构象。通过能量最小化计算得到了左手双链体的构象模型。因此，似乎DNA在某些受限条件下能够形成高反式左手双螺旋，这与Z-DNA的结构有很大不同。
