[Multiple forms of rabbit muscle phosphofructokinase revealed by means of specific elution]

The modified procedure for rabbit skeletal muscle phosphofructokinase (PFK) purification is worked out utioizing the method of specific elution from DEAE-cellulose in 0.1 M tris-EDTA-phosphate pH 8.0 with 10 mM citrate. By the latter procedure PFK can be resolved into fractions A, B and C which are eluted specifically, with 0.3 M buffer and with 1.5 M NaCl respectively. Rechromatography of each fraction reveals their interconvertibility. The preparations are characterized by disc electrophoresis and velocity sedimentation. The results of formalinization experiments demonstrate that high concentrations of formaldehyde dissociate PFK u to the 5.3 S component. The presence of the 19.3 S component in the formalinized preparations evidences against the possibility that the middle component, presented at the schlieren patterns of PFK at pH 8.0, is and artifact of superposition. Complex profiles of protein distribution observed in different transport experiments are discussed from the point of view of slow equilibrium of oligomers and conformers characteristic to PFK over the pH range from 6 to 9.