Phosphofructokinase from Escherichia coli: further evidence for identical subunits.

A procedure for the purification of Escherichia coli phosphofructokinase by affinity chromatography is described. The results of amino acid analyses of the purified protein and tryptic peptide mapping suggest that the tetrameric phosphofructokinase is composed of chemically identical subunits. In addition, the reaction product, ADP, was observed to bind to 4.1 +/- 0.1 equal and independent sites on the enzyme.