[Determination of the concentration of fructose-2,6-bisphosphate using phosphofructokinase].

: Measurement of fructose-2,6-bisphosphate (F-2,6-P2) level in biologic material is based on its ability to eliminate allosteric inhibition of phosphofructokinase (PFK) with high ATP concentrations. Effects of the buffer types and length of storage of commercial PFK from rabbit muscle, manufactured by Boehringer, on the enzyme ability to inhibit ATP and activate F-2,6-P2 were examined. The enzyme showed the highest sensitivity to ATP inhibition in tris buffer and the least one in morpholine propane sulfonic acid. If PFK is stored for a year its sensitivity to ATP inhibition and F-2,6-P2 activation essentially reduces and it becomes unfit for measurement of F-2,6-P2 concentration in biologic material.