title: A calorimetric study of the interaction of ATP with rabbit muscle phosphofructokinase.
abstract: The heat of interaction of ATP with phosphofructokinase from rabbit muscle was determined at 25 degrees C in 0.1 M potassium phosphate, pH 7.0 and 8.0. The limiting value of the enthalpy change at high ATP concentrations was found to be -11.5 kcal mol of enzyme polypeptide chains. Since phosphate and imidazole have very different heats of ionization (+0.8 and +7.5 kcal/mol, respectively), this suggests that the binding of at least two protons to the enzyme occurs concomitantly with the binding of ATP at the regulatory site.
mesh_terms: D000255:Adenosine Triphosphate; D000818:Animals; D002151:Calorimetry; D006863:Hydrogen-Ion Concentration; D009132:Muscles / Q000201:enzymology*; D010732:Phosphofructokinase-1 / Q000378:metabolism*; D011817:Rabbits
chemical_list: D000255:Adenosine Triphosphate; D010732:Phosphofructokinase-1