B中的关键阳离子平衡导致Z转变：Li⁺的作用。

Critical cation balance in B leads to Z transition: role of Li+.

作者信息

Ramesh N, Brahmachari S K

出版信息

FEBS Lett. 1983 Nov 28;164(1):33-7. doi: 10.1016/0014-5793(83)80013-1.

Abstract

The sodium salt of poly(dG-dC) is known to exhibit a B leads to Z transition in the presence of various cations and 60% alcohol. We here show that the lithium salt of poly(dG-dC) does not undergo B leads to Z transition in the presence of 60% alcohol since Li+ with its large hydration shell cannot stabilize the Z-form. On the other hand, high concentrations of Mg2+ or micromolar concentrations of the cobalt hexamine complex which are known to stabilize the Z-form can compete with Li+ for charge neutralization and hence bring about a B leads to Z transition in the same polymer. From the model building studies the mode of action of the cobalt-hexamine complex in stabilizing the Z-form is postulated.

摘要

已知聚（dG-dC）的钠盐在各种阳离子和60%乙醇存在的情况下会发生从B型到Z型的转变。我们在此表明，聚（dG-dC）的锂盐在60%乙醇存在的情况下不会发生从B型到Z型的转变，因为带有大水化层的Li⁺无法稳定Z型。另一方面，已知能稳定Z型的高浓度Mg²⁺或微摩尔浓度的六氨合钴配合物可以与Li⁺竞争电荷中和，从而使同一聚合物发生从B型到Z型的转变。通过模型构建研究推测了六氨合钴配合物稳定Z型的作用模式。