Sturm J, Zana R, Daune M
Biochim Biophys Acta. 1975 Sep 12;407(1):43-60.
A temperature-jump relaxation study of the interaction of hydroxystilbamidine with DNA and synthetic polynucleotides has been performed. Two concentration dependent relaxation times tau1 and tau2 have been observed in the submillisecond range when detecting relaxation effects by means of light absorption. The longer of these two times (tau1) is also observed when using "blue" or "red" fluorescence detection. In the longer time scale the "red" fluorescence shows no other relaxation but the blue fluorescence shows two additional relaxation processes (tau3 and tau4) which correspond to an increase of fluorescence with temperature and which are independent of concentration. The experimental results clearly indicate that tau1 and tau2 are associated with the binding of the dye to strong and weak binding sites, respectively. A kinetic model is given to explain the results. It allows the determination of the four rate constants for the two binding reactions and yields equilibrium association constants in good agreement with those obtained from stoichiometric studies. The study of the effect of temperature, nature of the polymer, ionic strength and fraction of bound dye on tau3 and tau4 indicates that the dye acts only as a "blue" fluorescence probe of some processes involving the DNA or polynucleotide alone. These processes appear to be related with the dynamic structure of the polymers.
已对羟基二脒与DNA及合成多核苷酸的相互作用进行了温度跃变弛豫研究。当通过光吸收检测弛豫效应时，在亚毫秒范围内观察到了两个浓度依赖性弛豫时间τ1和τ2。使用“蓝色”或“红色”荧光检测时，也观察到这两个时间中较长的那个（τ1）。在较长时间尺度上，“红色”荧光未显示其他弛豫，但“蓝色”荧光显示了另外两个弛豫过程（τ3和τ4），这两个过程对应于荧光随温度升高，且与浓度无关。实验结果清楚地表明，τ1和τ2分别与染料与强结合位点和弱结合位点的结合有关。给出了一个动力学模型来解释这些结果。它可以确定两个结合反应的四个速率常数，并得出与化学计量研究所得结果高度一致的平衡缔合常数。对温度、聚合物性质、离子强度和结合染料的比例对τ3和τ4的影响的研究表明，该染料仅作为某些仅涉及DNA或多核苷酸的过程的“蓝色”荧光探针。这些过程似乎与聚合物的动态结构有关。
