Bierzynski A, Kozlowska H, Wierzchowski K L
Biophys Chem. 1977 Apr;6(3):213-22. doi: 10.1016/0301-4622(77)85002-3.
A general equation was derived, describing fluorescence quantum yield and lifetime of an autoassociating compound in liquid solutions. The autoassociation of 2-aminopurine in aqueous solution was examined within the range from 0 to 90 degrees C. The compound seemed to associate cooperatively. The thermodynamic parameters of polymerization change with temperature, so that its free enthalypy deltaG = 0.0797 T2 + 45.4 T - 7893. The dimerization enthalpy and entropy are approximately temperature-independent (deltaH2 = -4.17 kcal/mol deltas2 = -10.9 e.u.), although the function: delta g2 = -0.0308T2 +30.3T - 7213 fits experimental points better. The observed dependences can be explained by the increasing role of the hydrophobic effect with temperature and size of the aggregates. The association rate constants were determined, and a two-step reaction mechanism was demonstrated. The first step is diffusion-controlled. The second is characterized by an activation energy of approximately 2 kcal/mol and an encounter distance of approximately 8.3 angstroms.
推导了一个描述液体溶液中自缔合化合物荧光量子产率和寿命的通用方程。在0至90摄氏度范围内研究了2-氨基嘌呤在水溶液中的自缔合。该化合物似乎协同缔合。聚合的热力学参数随温度变化，其自由焓变ΔG = 0.0797T² + 45.4T - 7893。二聚焓和熵与温度近似无关（ΔH₂ = -4.17千卡/摩尔，ΔS₂ = -10.9熵单位），尽管函数：ΔG₂ = -0.0308T² + 30.3T - 7213能更好地拟合实验点。观察到的依赖性可以通过疏水效应随温度和聚集体大小的作用增加来解释。确定了缔合速率常数，并证明了两步反应机理。第一步是扩散控制的。第二步的特征是活化能约为2千卡/摩尔，相遇距离约为8.3埃。
