Intramolecular DNA melting between stable helical segments: melting theory and metastable states.
Intramolecular DNA melting between stable helical segments: melting theory and metastable states.
复制标题
稳定螺旋段之间的分子内 DNA 熔化：熔化理论和亚稳态。
DOI：
10.1093/nar/23.14.2775
复制
发表时间：
1995
影响因子：
14.9
通讯作者：
Lerman,LS
中科院分区：
文献类型：
--
作者：
Abrams,ES;Murdaugh,SE;Lerman,LS
DNA的解链在变性梯度凝胶中，在解链过程中，两端由更稳定的区域限定的片段显示出复杂的性质，不符合标准的解链理论。在变性梯度中，某些DNA分子的致密条带在阻滞水平上变得异常增宽，或者在均匀的变性剂浓度下出现双条带。这些性质仅与由Poland-Hxman-Freire算法计算的稳定性分布指示最低稳定性区域不延伸到分子末端的分子相关。末端螺旋度的保持通过末端结构域和最不稳定结构域中碱基取代的效果的差异来显示。双谱带的出现和谱带的展宽都可以通过在熔化过程中假设一个亚稳中间体的存在来解释，该中间体以相对缓慢的速率转化为平衡熔化形式，这取决于变性剂浓度和场强。一个动力学模型允许似是而非的速率常数推断的模式。尽管增加了带宽，但在最不稳定结构域中具有碱基变化的序列变体导致在梯度中容易检测到的条带移位。
Melting of DNA In a segment bounded at both ends by regions of greater stability during electrophoresls in denaturing gradient gels shows complex properties, not accommodated within standard melting theory. Compact bands of some DNA molecules become anomalously broadened at the retardation level in a denaturing gradient, or double bands may appear in a uniform denaturant concentration. These properties are associated only wfth molecules for which the distribution of stability calculated by the Poland-Hxman-Freire algorithms indicates that the region of lowest stability does not extend to an end of the molecule. Retention of helicity at the ends is shown by the difference in the effect of base substitution In the end domains and in the least stable domain. Both the appearance of double bands and band broadening can be explained by Invoking a hypothetical metastable Intermediate in melting, which is converted Into the equilibrium melted form at a relatively slow rate, depending on both denaturant concentration and field strength. A kinetic model permits plausible rate constants to be inferred from the patterns. Despite the increased band width, sequence variants with base changes in the least stable domain result in readily detectable band shifts in the gradient.