Bierzyński A, Kollowska H, Proba Z, Wierzchowski K L
Biophys Chem. 1977 Apr;6(3):231-7. doi: 10.1016/0301-4622(77)85004-7.
General equations relating fluorescence quantum yield and lifetime of a compound with its intramolecular stacking equilibrium and kinetics were derived. Intramolecular stacking association of 9,9'-[1,3-propylene]-bis-2-aminopurine in aqueous solution was examined within the range of temperatures from 0 to 90 degrees C. A two-state thermodynamic model of the association was verified. The stacking enthalpy and entropy can be taken, with a good approximation, as temperature-independent (deltaH equals - 2.0 kcal/mol, deltaS=-3.25 e.u.) although the function deltaG=-0.00886T2 + 8.847 T - 2876 describes more precisely the observed changes of stacking free enthalpy with temperature. The association rate constants were detemined. Activation energy of the reaction (2 kcal/mol) is the same as in the case of association between free 2-aminopurine molecules. It confirms a two-step mechanism of the process. The advantages and shortcomings of the fluorescence quenching method are discussed.
推导了将化合物的荧光量子产率和寿命与其分子内堆积平衡及动力学相关联的通用方程。在0至90摄氏度的温度范围内研究了9,9'-[1,3-亚丙基]-双-2-氨基嘌呤在水溶液中的分子内堆积缔合。验证了该缔合的双态热力学模型。尽管函数ΔG = -0.00886T² + 8.847T - 2876能更精确地描述堆积自由焓随温度的观测变化，但堆积焓和熵在良好近似下可视为与温度无关（ΔH = -2.0千卡/摩尔，ΔS = -3.25熵单位）。测定了缔合速率常数。反应的活化能（2千卡/摩尔）与游离2-氨基嘌呤分子之间缔合的情况相同。这证实了该过程的两步机制。讨论了荧光猝灭法的优缺点。
