作者:Vipin Kumar、Venkitasamy Kesavan
DOI:10.1039/c3ra41255e
日期:——
The construction of an A-switch, derived from the artificial nucleic acid called acyclic Butyl Nucleic Acid (BuNA) was accomplished. The phosphoramidite building blocks of (S)-BuNA were synthesized from (R)-aspartic acid. To demonstrate its use as an A-switch, a stretch of polyadenine nucleotides of (S)-BuNA was studied by circular dichroism (CD) and ultraviolet (UV) spectroscopy under neutral and acidic conditions. Acid–base titration revealed two state transitions at pH 4.8 and highly pH-dependent structural conformation reversibility. Thermal melting (Tm) studies suggest that at neutral pH, poly BuNA(A) is a weakly organized single strand, while at low pH it adopts a highly organized and rigid structure. Furthermore, MALDI-TOF-MS data revealed intermolecular interactions which led to the formation of an A-motif composed of a double helical structure. Since BuNA does not suffer from depurination under acidic conditions, this allowed us to determine the thermodynamic parameters of the A-motif. This is the first report of the construction of an A-switch using artificial nucleic acids.
构建了一种A开关,该开关源自一种名为无环丁基核酸(BuNA)的人工核酸。首先,合成了(S)-BuNA的磷酰胺化学构件,原料为(R)-天冬氨酸。为了展示其作为A开关的用途,研究了(S)-BuNA的聚腺苷酸核苷酸序列在中性和酸性条件下的圆二色性(CD)和紫外光(UV)光谱。酸碱滴定揭示了在pH 4.8处的两个状态转变以及高度pH依赖的结构构象可逆性。热融化(Tm)研究表明,在中性pH下,聚BuNA(A)是一个弱有序的单链,而在低pH下,它则采用高度有序和刚性结构。此外,MALDI-TOF-MS数据显示出分子间的相互作用,这导致形成了由双螺旋结构组成的A基元。由于BuNA在酸性条件下不会发生去嘌呤作用,这使我们能够确定A基元的热力学参数。这是首次报道使用人工核酸构建A开关。