DNA denaturation in situ. Effect of divalent cations and alcohols.
DNA denaturation in situ. Effect of divalent cations and alcohols.
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DOI：
10.1083/jcb.68.1.1
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发表时间：
1976-01
影响因子：
7.8
通讯作者：
Melamed, M R
中科院分区：
文献类型：
--
作者：
Darzynkiewicz, Z;Traganos, F;Sharpless, T;Melamed, M R
大鼠胸腺DNA的热变性概况，在完整的细胞，揭示了存在两个主要的DNA组分不同的敏感性，以热。热敏DNA部分显示出与游离DNA相似的某些性质：其对热的稳定性被醇降低，并且在浓度为0.1- 1.0mM的二价阳离子Ca 2+、Mn 2+或Mg 2+存在下增加。然而，与游离DNA不同，该级分在宽的温度范围内变性，并且是不均匀的，由至少两种具有不同熔点的亚组分组成。耐热性DNA级分在Ca 2+、Mn 2+或Mg 2+的存在下显示出降低的热稳定性，而在醇的存在下显示出增加的稳定性。它在相对较窄的温度范围内变性，由至少三个亚组分组成，并且很可能代表被组蛋白掩蔽的DNA。Ca 2+、Mn 2+或Mg 2+在降低耐热性DNA部分的熔点中的作用在与维持细胞核中的总染色质结构或支持分离的染色质中的超螺旋DNA构象所需的阳离子浓度（0.5-1.0 mM）相当的阳离子浓度下观察到。可能的是，参与维持原位总染色质组织和/或与DNA超螺旋性相关的因素也在调节DNA-组蛋白相互作用中起作用，并且使用分离的染色质的常规方法所揭示的DNA-蛋白质相互作用可能不同于当总染色质形态保持完整时所揭示的那些。
Heat denaturation profiles of rat thymus DNA, in intact cells, reveal the presence of two main DNA fractions differing in sensitivities to heat. The thermosensitive DNA fraction shows certain properties similar to those of free DNA: its stability to heat is decreased by alcohols and is increased in the presence of the divalent cations Ca2+, Mn2+, or Mg2+ at concentrations of 0.1-1.0 mM. Unlike free DNA, however, this fraction denatures over a wide range of temperature, and is heterogeneous, consisting of at least two subfractions with different melting points. The thermoresistant DNA fraction shows lowered stability to heat in the presence of Ca2+, Mn2+, or Mg2+ and increased stability in the presence of alcohols. It denatures within a relatively narrow range of temperature, consists of at least three subfractions, and, most likely, represents DNA masked by histones. The effect of Ca2+, Mn2+, or Mg2+ in lowering the melting point of the thermoresistant DNA fraction is seen at cation concentrations comparable to those required to maintain gross chromatin structure in cell nuclei or to support superhelical DNA conformation in isolated chromatin (0.5-1.0 mM). It is probable that factors involved in the maintenance of gross chromatin organization in situ and/or related to DNA superhelicity also have a role in modulating DNA-histone interactions, and that DNA-protein interactions as revealed by conventional methods using isolated chromatin may be different from those revealed when gross chromatin morphology remains intact.