Modeling ATP protonation and activity coefficients in NaClaq and KClaq by SIT and Pitzer equations.
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.
De Stefano
Concetta
C
Dipartimento di Chimica Inorganica, Chimica Analitica e Chimica Fisica, Università di Messina, Salita Sperone, 31, I-98166 Messina, Vill. S. Agata, Italy.
Milea
Demetrio
D
Pettignano
Alberto
A
Sammartano
Silvio
S
D000255:Adenosine Triphosphate / Q000737:chemistry*; D004563:Electrochemistry; D009994:Osmolar Concentration; D011189:Potassium Chloride / Q000737:chemistry*; D012965:Sodium Chloride / Q000737:chemistry*
D012965:Sodium Chloride; D011189:Potassium Chloride; D000255:Adenosine Triphosphate