De Stefano Concetta, Milea Demetrio, Pettignano Alberto, Sammartano Silvio
Dipartimento di Chimica Inorganica, Chimica Analitica e Chimica Fisica, Università di Messina, Salita Sperone, 31, I-98166 Messina, Vill. S. Agata, Italy.
Biophys Chem. 2006 May 20;121(2):121-30. doi: 10.1016/j.bpc.2005.12.016. Epub 2006 Feb 20.
The acid-base properties of Adenosine 5'-triphosphate (ATP) in NaCl and KCl aqueous solutions at different ionic strengths (0<I/mol L(-1)<or=5 for NaCl(aq), 0<I/mol L(-1)<or=3 for KCl(aq)) and at t=25 degrees C were investigated. A selection of literature data on ATP protonation constants and on activity isopiestic coefficients was performed, together with new potentiometric measurements (by ISE-H(+), glass electrode). Both literature and new experimental data were used to model the dependence on ionic strength and ionic medium of ATP protonation by SIT (Specific ion Interaction Theory) and Pitzer equations. In addition to values of first and second ATP protonation constants in NaCl(aq) and KCl(aq) at different ionic strengths, stability constants of NaATP(3-) and KATP(3-) complexes, SIT interaction coefficients and Pitzer parameters were calculated, together with protonation constants at infinite dilution: log (T)K(1)(H)=p(T)K(a2)=7.656+/-0.010 and log (T)K(2)(H)=p(T)K(a1)=4.561+/-0.006 (in the molar concentration scale, +/-95% confidence interval). Both SIT and Pitzer approaches give satisfactory results.
研究了在25℃下，不同离子强度（对于NaCl水溶液，0＜I/mol L⁻¹≤5；对于KCl水溶液，0＜I/mol L⁻¹≤3）的NaCl和KCl水溶液中腺苷5'-三磷酸（ATP）的酸碱性质。选取了有关ATP质子化常数和活度等压系数的文献数据，并进行了新的电位测量（使用ISE-H⁺玻璃电极）。利用文献数据和新的实验数据，通过特定离子相互作用理论（SIT）和皮兹方程对ATP质子化对离子强度和离子介质的依赖性进行建模。除了不同离子强度下NaCl水溶液和KCl水溶液中ATP的一级和二级质子化常数的值外，还计算了NaATP³⁻和KATP³⁻配合物的稳定常数、SIT相互作用系数和皮兹参数，以及无限稀释时的质子化常数：log(T)K₁(H)=p(T)Kₐ₂ = 7.656±0.010和log(T)K₂(H)=p(T)Kₐ₁ = 4.561±0.006（在摩尔浓度标度下，±95%置信区间）。SIT和皮兹方法都给出了令人满意的结果。
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