Shchelkina A K, Borisova O F, Churikov N A, Chernov B K
Mol Biol (Mosk). 1992 Nov-Dec;26(6):1327-31.
Conformations of parallel deoxyoligonucleotides 5'd(CTATAGGGAT)3'/5'd(GATATCCCTA)3' and 5'd(TGATTGATCGATTGTTTGCATGCACACGTTTTTGTGAGCG)3'/'5'd (ACTAACTAGCTAACAAACGTACGTGTGCAAAAACACTCGC)3' were studied in solution by CD method. A cooperative change in the CD spectra is observed in trifluoroethanol (TFE) solutions at decreased water activity (relative humidity). This distinctive change is supposed to stem from a cooperative conformational transition of parallel double helix from a B-like form with C2'endo sugar conformation to a A-like form designated as Ap. The free energy difference between Ap- and B-like conformations of the parallel decaduplex is close to that for antiparallel decaduplex with the nucleotide sequence studied. A-phility of a parallel helix is dependent on its sequence.
通过圆二色光谱法在溶液中研究了平行脱氧寡核苷酸5'd(CTATAGGGAT)3'/5'd(GATATCCCTA)3'和5'd(TGATTGATCGATTGTTTGCATGCACACGTTTTTGTGAGCG)3'/'5'd (ACTAACTAGCTAACAAACGTACGTGTGCAAAAACACTCGC)3'的构象。在水活度降低（相对湿度）的三氟乙醇（TFE）溶液中观察到圆二色光谱的协同变化。这种独特的变化被认为源于平行双螺旋从具有C2'内型糖构象的B样形式到指定为Ap的A样形式的协同构象转变。平行十聚双链体的Ap构象和B样构象之间的自由能差与所研究核苷酸序列的反平行十聚双链体的自由能差相近。平行螺旋的A亲合性取决于其序列。
