Ionic and structural effects on the thermal helix‐coil transition of DNA complexed with natural and synthetic polyamines
Ionic and structural effects on the thermal helix‐coil transition of DNA complexed with natural and synthetic polyamines
复制标题
离子和结构对天然和合成多胺复合 DNA 热螺旋-螺旋转变的影响
作者：
T. Thomas;V. Bloomfield
多胺是一种普遍存在的细胞成分，与核酸相互作用强烈。虽然许多寡核苷酸与DNA的相互作用可以用将反离子视为点电荷的聚电解质理论来解释，但一些结构效应是明显的。我们用一系列亚精胺类似物NH_3(CH_2)_3NH_2(CH_2)nNH_ ~(33+)探索了多胺结构对DNA行为的一个重要方面--热熔化转变的影响，其中n从2到8[Jorstad et al.(1980)J.细菌素。141,456-463]。对于亚精胺本身，n=4。在这些类似物以及其他自然存在的多胺腐胺2+和精胺4+存在的情况下，测量了小牛胸腺DNA在广泛的氯化钠浓度和多胺：DNA磷酸比率范围内的Tm。这带来了温和但重大的结构性影响。尤其是较短的n=2和3导数，其几何构型可能不允许与DNA完全静电相互作用。另一方面，较长的类似物在对TM的影响方面与亚精胺没有太大区别，尽管在n=5时有一个中等的最大值。由于多胺在细胞凝聚和DNA的包装中很重要，我们也描述了引起DNA聚集所需的临界多胺和盐浓度。这里又一次出现了重大的结构性影响，任何简单的考虑都不能轻易将其合理化。
Polyamines are ubiquitous cellular components that interacts strongly with nucleic acids. Although many of the interactions of oligocations with DNA can be rationalized with polyelectrolyte theories that treat counterions as point charges, some structural effects are evident. We have explored the effects of polyamine structure on one important aspect of DNA behavior, its thermal melting transition, by using a series of spermidine analogs NH3(CH2)3NH2(CH2)nNH 33+ , where n varies from 2 to 8 [Jorstad et al. (1980) J. Bacteriol. 141, 456–463]. For spermidine itself, n = 4. Tm for calf‐thymus DNA in the presence of each of these analogs, and the other naturally occurring polyamines putrescine2+ and spermine4+, was measured over a wide range of NaCl concentrations and polyamine:DNA phosphate ratios. There are modest, but significant structural effects. particularly with the shorter n = 2 and 3 derivatives, whose geometry my not allow full electrostatic interaction with DNA. Longer analogs, on the other hand, are not much different than spermidine in their effects on Tm, though a moderate maximum occurs at n = 5. Since polyamines are important in the cellular condensation and packaging of DNA, we have also delineated the critical polyamine and salt concentrations that are required to cause DNA aggregation. Here again, there are significant structural effects, which are not easily rationalized by any simple considerations.
影响因子：
5.6
作者：
WIDOM, J;BALDWIN, RL
通讯作者：
BALDWIN, RL
DOI：
--
发表时间：
1982
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Krasnow,MA;Cozzarelli,NR
通讯作者：
Cozzarelli,NR