Takeuchi S, Maeda A
Biochim Biophys Acta. 1979 Jul 26;563(2):365-74. doi: 10.1016/0005-2787(79)90055-8.
Fluorescein mercuric acetate causes the unwinding of DNA and binds to the separated bases. The kinetics of this unwinding process were studied using both untreated DNA and sonicated DNA at various pH values (6.8--9.3) and Na+ concentrations (10--250 mM). The unwinding process is explained by assuming a nucleation in the middle of DNA (as a function of time) as well as at the helix ends (immediately after addition of this reagent) and the subsequent growth of the nuclei. The frequency of the nucleation in the middle of DNA appears to be markedly affected by pH and Na+ concentration. In contrast, the reaction rate of this reagent with heat-denatured DNA was almost insensitive to these environmental variables. The growth rate of the unwinding nuclei in double-stranded DNA also appears insensitive. The most important implication of this study is that in the low pH range (6.8--7.5) the reactivity of thermally-induced locally open regions in the middle of double-helical DNA toward this reagent appears much higher than that of heat-denatured DNA. Since this reagent is negatively charged, these findings are discussed in view of its electrostatic interaction with the locally open regions.
荧光素汞醋酸盐会导致DNA解旋并与分离的碱基结合。在不同的pH值（6.8 - 9.3）和Na⁺浓度（10 - 250 mM）下，使用未处理的DNA和超声处理的DNA研究了这种解旋过程的动力学。通过假设DNA中间（作为时间的函数）以及螺旋末端（加入该试剂后立即）的成核作用以及随后核的生长来解释解旋过程。DNA中间的成核频率似乎受到pH值和Na⁺浓度的显著影响。相比之下，该试剂与热变性DNA的反应速率对这些环境变量几乎不敏感。双链DNA中解旋核的生长速率似乎也不敏感。这项研究最重要的意义在于，在低pH范围（6.8 - 7.5）内，双螺旋DNA中间热诱导的局部开放区域对该试剂的反应性似乎比热变性DNA高得多。由于该试剂带负电荷，鉴于其与局部开放区域的静电相互作用对这些发现进行了讨论。
