Various modified guanine derivatives were synthesized and introduced into G(4) of d(CGCGCG)(2) to evaluate their capacity to stabilize Z-form DNA. It was found that the incorporation of 8-methylguanosine (m(8)rG) in oligonucleotides stabilizes the Z form more dramatically than does the incorporation of 8-methyl-2'-deoxyguanosine (m(8)G). This enhancement is ascribed to a reduction in the entropic penalty, which arises from the introduction of hydrophilic groups in solvent-exposed regions. The incorporation of m(8)rG into DNA sequences markedly stabilizes the Z form even in the absence of NaCl. The Z-DNA stabilizer allows oligonucleotides with a wide range of sequences to be converted to the Z form. It could be a powerful tool for examining the molecular basis of many types of Z-form-specific reactions at the molecular level under physiological salt conditions.

中文翻译：

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8-甲基鸟苷：强大的 Z-DNA 稳定剂

各种修饰的鸟嘌呤衍生物被合成并引入到 d(CGCGCG)(2) 的 G(4) 中以评估它们稳定 Z 型 DNA 的能力。发现在寡核苷酸中掺入 8-甲基鸟苷 (m(8)rG) 比掺入 8-甲基-2'-脱氧鸟苷 (m(8)G) 更显着地稳定 Z 形式。这种增强归因于熵损失的减少，这是由于在溶剂暴露区域引入亲水基团引起的。即使在没有 NaCl 的情况下，将 m(8)rG 纳入 DNA 序列也能显着稳定 Z 形式。Z-DNA 稳定剂允许具有广泛序列的寡核苷酸转化为 Z 形式。