Three dinucleoside monophosphates containing 8, 2'-anhydro-8-thio-9-β-D-arabinofuranosyladenine (As) and its hypoxanthine derivative (Is), AspIs, IspAs and IspIs, were synthesized. Examination of their properties by ultraviolet absorption, circular dichroism and 1H nuclear magnetic resonance measurements and comparison with the properties of AspAs, which has been shown to take a left-handed stacked conformation, showed that all these dimers take a left-handed stacked conformation, and the order of extent of stacking is AspAs≈IspAs>AspIs≈IspIs. This sequence dependency of stability of stacking can be explained in terms of the mode of base-base overlap in a left-handed stack. A similar explanation may be applicable to the corresponding sequence dependency of natural dimers with a right-handed stack.
合成了三种含有8,2'-去氧-8-
硫-9-β-D-阿拉伯
呋喃糖基
腺嘌呤(As)及其
次黄嘌呤衍
生物(Is)的二核苷酸单
磷酸盐:AspIs, IspAs和IspIs。通过紫外吸收、圆二色性和氢核磁共振测量对其性质进行检验,并与已知呈左手堆积构象的AspAs的性质进行比较,结果表明所有这些二聚体均呈左手堆积构象,堆积程度的顺序为AspAs≈IspAs>AspIs≈IspIs。这种稳定性的序列依赖性可以用左手堆积中碱基重叠的方式来解释。类似的解释可能也适用于相应天然二聚体右手堆积中的序列依赖性。