Differential dissociation of histone tails from core chromatin.
Differential dissociation of histone tails from core chromatin.
复制标题
组蛋白尾部与核心染色质的差异解离。
DOI：
--
复制
发表时间：
1984
期刊：
影响因子：
--
通讯作者：
Walker Io
中科院分区：
文献类型：
--
作者：
Walker Io
核心染色质核心组蛋白的胰蛋白酶敏感碱性尾的解离已被质子核磁共振波谱作为[NaCl]的函数跟踪。在盐浓度0.2-0.6 M范围内，即低于解离完整分子所需的盐浓度，尾部以高度合作的全部或不解离的方式解离。假设每个基本尾巴都独立分离，则尾巴与DNA结合的盐键总数为103。这等于一个八聚体尾部的基本侧链的数目。297 K下，1 M NaCl的标准离解自由能G度为3.6 kcal/mol。温度在45℃以下对解离程度没有影响。然而，在45℃至65℃之间，核染色质发生预熔转变，尾部完全解离。尾巴的解离与DNA的构象转变有关，与超卷曲的损失一致。从这一点和先前的研究结果可以看出，每个核心组蛋白八聚体的结构化、抗胰蛋白酶结构域与DNA形成了100个盐键。因此，在10毫米的盐中，每个核心八聚体与DNA形成了总共203个盐链。
: The dissociation of the trypsin-sensitive basic tails of the core histones in core chromatin has been followed as a function of [NaCl] using proton NMR spectroscopy. The tails dissociate in a highly cooperative all or none manner over the salt concentration range 0.2-0.6 M, that is, below the salt concentration required to dissociate the complete molecule. Assuming that each basic tail dissociates independently, the total number of salt linkages involved in binding the tails to DNA is 103. This equals the number of basic side chains in the tails of an octamer. The standard free energy of dissociation, delta G degree, in 1 M NaCl at 297 K is 3.6 kcal/mol. Temperature had no effect on the extent of dissociation up to 45 degrees C. However, between 45 and 65 degrees C, where the premelting transition in the core chromatin occurs, the tails dissociated completely. Dissociation of the tails was associated with a conformational transition in the DNA consistent with loss of supercoiling. From this, and the results of a previous study, it can be shown that the structured, trypsin-resistant domain of each core histone octamer makes 100 salt linkages to DNA. Thus, in 10 mM salt, each core octamer makes a total of 203 salt linkages to DNA.