Thermodynamic study of the formation of adenine nucleotide-manganese complexes. I. "pH stat" titration method results.

The thermodynamics associated with the Mn2- -ATP, Mn-ADP- and Mn-AMP complex formation reactions determined from K potentiometric measurements at I = 0.2 are reported for the temperature range 1--45 degrees C. The K values increase with the length of the phosphate chain and with temperature. The limits and the best conditions for use of the "pH stat" titration method are discussed. Comparison with the results obtained by potentiometric and calorimetric methods in the case of Mg-nucleotide complexes is made.