Control of phosphofructokinase from the phasic adductor muscle of the bay scallop, Argopecten irradians concentricus

Abstract

1. 1. Phosphofructokinase (PFK) purified from the adductor muscle of Argopecten irradians concentricus showed sigmoidal saturation kinetics with respect to F-6-P in the physiological range of pH from 6.8 to 7.2. The saturation curve with respect to ATP showed typical substrate inhibition. 2. 2. Decreases in pH resulted in lower binding capacity of PFK for F-6-P as well as stronger inhibition by ATP. 3. 3. Both AMP and F-2,6-P activated adductor muscle PFK by shifting the F-6-P saturation curve from sigmoidal to hyperbolic. The presence of AMP also relieved the inhibitory effect of ATP. 4. 4. Phosphoenolpyruvate, fructose-1,6-P and inorganic phosphate were inhibitory to adductor muscle PFK. Arginine phosphate had no effect on the activity of PFK.