Blagoĭ Iu P, Sorokin V A, Valeev V A, Gladchenko G O
Mol Biol (Mosk). 1978 Jul-Aug;12(4):795-805.
Using the thermal denaturation method the effect of bivalent copper of (4-10(-6)-10(-3)) M concentrations on the helix-coil transition of DNA was studied in the solution of Na+ concentrations 10(-3)-10(-1) M. Unlike the previous studies, this paper makes allowance for the effect of impurity ions present in DNA and deionized water. It has been shown that in the region of low Cu2+ and Na+ concentrations, thermal stability increases, the melting range extends and the denaturation curves become asymmetric. At concentrations more than approximately 3-10(-5) M Cu2+, melting temperature starts to fall, and the range reduces to 1-1.5 degrees at [Cu2+] greater than or equal to 2-10(-4) M. As [Cu2+] reaches these values, the denaturation curve asymmetry and melting range increase again, which is due to the inversion of the relative stability of AT- and GC-pairs. Employing experimental and phase-transition-theory data for homopolymers, the constants of Cu2+ binding with phosphates and DNA bases were calculated. The concentration dependence of the DNA denaturation parameters was shown to be governed by the superposition of binding Cu2+ with phosphates and nucleic acid bases.
采用热变性方法，在钠离子浓度为10⁻³ - 10⁻¹ M的溶液中，研究了浓度为(4 - 10⁻⁶ - 10⁻³) M的二价铜对DNA螺旋-线圈转变的影响。与之前的研究不同，本文考虑了DNA和去离子水中存在的杂质离子的影响。结果表明，在低铜离子和钠离子浓度区域，热稳定性增加，熔解范围扩大，变性曲线变得不对称。当铜离子浓度超过约3 - 10⁻⁵ M时，熔解温度开始下降，在[Cu²⁺]≥2 - 10⁻⁴ M时，范围缩小至1 - 1.5摄氏度。当[Cu²⁺]达到这些值时，变性曲线的不对称性和熔解范围再次增加，这是由于AT对和GC对相对稳定性的反转。利用均聚物的实验和相变理论数据，计算了铜离子与磷酸盐和DNA碱基结合的常数。结果表明，DNA变性参数的浓度依赖性受铜离子与磷酸盐和核酸碱基结合的叠加作用控制。
