Fazakerley G V, Kraszewski A, Téoule R, Guschlbauer W
Nucleic Acids Res. 1987 Mar 11;15(5):2191-201. doi: 10.1093/nar/15.5.2191.
The hexamer d(CGm4CGCG) exists predominantly as a right handed B form helix at 20 degrees C in 150 mM NaCl, as shown by 2D NOE spectra. Under these conditions a minor species is also observed which corresponds to the single strand in slow exchange on a proton NMR time scale with the double strand. This exchange is unusually slow and separate resonances for the two species are seen up to 65 degrees C. At 50 degrees C the lifetime of the single strand species is 0.85 s. Under high salt conditions the hexamer is partly converted into the Z form, but the complete transition is only observed at 5M NaCl at -6 degrees C.
二维NOE谱表明,六聚体d(CGm4CGCG)在150 mM NaCl中、20℃时主要以右手B型螺旋形式存在。在这些条件下,还观察到一种次要物种,它在质子NMR时间尺度上与双链进行缓慢交换,对应于单链。这种交换异常缓慢,在高达65℃时仍能看到两种物种的独立共振峰。在50℃时,单链物种的寿命为0.85秒。在高盐条件下,六聚体部分转化为Z型,但只有在-6℃、5M NaCl时才观察到完全转变。