CONTROL OF REDUCED DIPHOSPHOPYRIDINE NUCLEOTIDE OSCILLATIONS IN BEEF HEART EXTRACTS .3. PURIFICATION AND KINETICS OF BEEF HEART PHOSPHOFRUCTOKINASE

Phosphofructokinase was purified extensively from beef heart and studied kinetically at pH 6.25 and low hexose-monophosphate concentrations to observe its behavior under conditions similar to those prevailing in cell-free extracts with oscillatory control. Adenosine 5′-triphosphate was a very powerful inhibitor at this pH, and the inhibition was prevented by AMP, ADP, and FDP. Adenosine 5′-monophosphate induced an activation even when the ATP concentration was kept below its inhibitory value. The results indicate that the DPNH oscillations observed in cell-free extracts are probably due to the variable activity of phosphofructokinase under the influence of the adenine nucleotides and fructose 1,6-diphosphate. © 1968.