Mellema J R, Pieters J M, van der Marel G A, van Boom J H, Haasnoot C A, Altona C
Eur J Biochem. 1984 Sep 3;143(2):285-301. doi: 10.1111/j.1432-1033.1984.tb08371.x.
The two deoxyribotetranucleoside triphosphates d(T-A-T-A) and d(A-T-A-T) were investigated in aqueous solution by one- and two-dimensional proton NMR at 300 and 500 MHz. It is demonstrated that both compounds occur predominantly in the single-helical form. Accurate coupling constants are obtained by computer simulation of several 500-MHz spectra. The data are interpreted in terms of N and S pseudorotational ranges. The geometry of the major S-type conformers displays a clear sequence dependence, as expressed by variation of the endocyclic backbone angle delta (C5'-C4'-C3'-O3'). A simple sum rule is proposed to predict delta variation in single-helical DNA fragments. Comparisons are made with other sequence-dependent geometries as observed in a double-helical B-DNA fragment in the crystalline state. Furthermore, one- and two-dimensional nuclear Overhauser effect (NOE) spectroscopy was carried out on d(T-A-T-A). An inventory is made of the observed intra- and inter-residue NOEs. The NOE data confirm the presence of a highly stacked single-helical conformation of d(T-A-T-A) in solution. No indications are found for the formation of a bulge-out structure as observed for analogous alternating purine-pyrimidine oligoribonucleotides.
通过在300兆赫和500兆赫下的一维和二维质子核磁共振，对两种脱氧核糖四核苷三磷酸d(T-A-T-A)和d(A-T-A-T)在水溶液中进行了研究。结果表明，这两种化合物主要以单螺旋形式存在。通过对几个500兆赫光谱进行计算机模拟获得了精确的耦合常数。根据N和S假旋转范围对数据进行了解释。主要S型构象体的几何形状表现出明显的序列依赖性，以内环主链角δ（C5'-C4'-C3'-O3'）的变化来表示。提出了一个简单的求和规则来预测单螺旋DNA片段中的δ变化。与在结晶状态下双螺旋B-DNA片段中观察到的其他序列依赖性几何形状进行了比较。此外，对d(T-A-T-A)进行了一维和二维核Overhauser效应（NOE）光谱分析。列出了观察到的残基内和残基间NOE。NOE数据证实了溶液中d(T-A-T-A)存在高度堆积的单螺旋构象。未发现形成类似交替嘌呤-嘧啶寡核糖核苷酸中观察到的突出结构的迹象。
