肌苷取代鸟苷对DNA稳定性产生的序列依赖性影响。
Sequence-dependent effects on DNA stability resulting from guanosine replacements by inosine.
作者信息
Reich N O, Sweetnam K R
机构信息
U.C. Santa Barbara, Department of Chemistry 93106.
出版信息
Nucleic Acids Res. 1994 Jun 11;22(11):2089-93. doi: 10.1093/nar/22.11.2089.
The effect of replacing a G.C base-pair with an I.C base-pair on DNA stability was investigated for a related set of 14-mers. DNA melting analysis of the 14-mers was used to determine delta Hzero, delta Szero and delta G(zero)37 of the double to single stranded transition. All 14mers were shown to have B-DNA character by circular dichroism analysis. 14mers substituted with a single inosine in place of guanosine at different positions showed that consequences on DNA stability are sequence-dependent. Large changes in delta Hzero and delta Szero result when inosine is substituted within the trinucleotide sequence d(TCG).d(CGA) while substitution within d(TCC).d(GGA) causes minor changes in enthalpy and entropy. Moreover, some 14-mers with two inosine substitutions five base-pairs apart showed non-additive free energy changes for the double to single stranded transition. These results clearly indicate that the structural consequences of replacing a single guanosine with an inosine are transmitted over a significant distance.
对于一组相关的14聚体，研究了用肌苷-胞嘧啶碱基对取代鸟嘌呤-胞嘧啶碱基对（G.C）对DNA稳定性的影响。通过对14聚体进行DNA熔解分析，以确定双链到单链转变的标准焓变（ΔH⁰）、标准熵变（ΔS⁰）和37℃时的标准自由能变（ΔG⁰₃₇）。通过圆二色性分析表明，所有14聚体均具有B-DNA特征。在不同位置用单个肌苷取代鸟苷的14聚体显示，对DNA稳定性的影响取决于序列。当在三核苷酸序列d(TCG).d(CGA)中用肌苷取代时，ΔH⁰和ΔS⁰会发生很大变化，而在d(TCC).d(GGA)中进行取代时，焓和熵的变化较小。此外，一些在相隔五个碱基对处有两个肌苷取代的14聚体，其双链到单链转变的自由能变化是非加和性的。这些结果清楚地表明，用肌苷取代单个鸟苷的结构后果会在相当长的距离上传递。
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