Hartmann B, Thuong N T, Pouyet J, Ptak M, Leng M
Nucleic Acids Res. 1983 Jul 11;11(13):4453-66. doi: 10.1093/nar/11.13.4453.
The hexanucleoside pentaphosphate d(m5CpGpm5CpGpm5CpG) has been studied in solution by ultra-violet absorption, circular dichroism and 31P nuclear magnetic resonance under various experimental conditions. In 0.2 M NaClO4 at low temperature, an hexamer duplex is formed which has a B or B-like conformation. As the salt concentration is increased, a transition from a B-form to the Z-form occurs and is complete in 3 M NaClO4. In 3 M NaClO4, the behavior of the Z double helix is complex as a function of temperature. The variation of the circular dichroism at 295 nm is biphasic. A first transition occurs over a large range of temperature and corresponds to a conformational change due to a non-cooperative intramolecular process. Ultra-violet absorption and 31P nuclear magnetic resonance show that the new conformation arising from a distortion of the backbone is not similar to that observed in low salt conditions (B-form). At high hexanucleotide concentration, aggregates are formed. The second transition is cooperative and corresponds to the melting of a double stranded helix into single strands.
已通过紫外吸收、圆二色性和³¹P核磁共振在各种实验条件下对六核苷五磷酸d（m⁵CpGpm⁵CpGpm⁵CpG）在溶液中的情况进行了研究。在低温下的0.2 M高氯酸钠中，形成了具有B或类B构象的六聚体双链体。随着盐浓度的增加，会发生从B型到Z型的转变，在3 M高氯酸钠中转变完成。在3 M高氯酸钠中，Z型双螺旋的行为随温度变化较为复杂。295 nm处圆二色性的变化是双相的。第一个转变在较大温度范围内发生，对应于由于非协同分子内过程导致的构象变化。紫外吸收和³¹P核磁共振表明，由主链扭曲产生的新构象与在低盐条件下观察到的构象（B型）不同。在高六核苷酸浓度下，会形成聚集体。第二个转变是协同的，对应于双链螺旋熔解为单链。
