Phosphofructokinase from Ascaris suum. Regulatory kinetic studies and activity near physiological conditions.

The regulatory kinetic properties of the phospho form of phosphofructokinase (1.5 to 2 phosphates covalently bound/subunit) from the muscle of Ascaris suum have been studied.The enzyme is inhibited by ATP at both pH 6.6 and 8.0.This inhibition cannot be completely overcome at either pH by increasing the fructose 6-phosphate (Fru-6-P) concentration to as high as 40 m~.At 1 m~ ATP, the F'ru-6-P saturation curve exhibited cooperativity (Hill coefficient, 1.5) and AMP was the only compound tested that would effectively shift the curve to a hyperbolic shape.The presence of