Comparison of muscle phosphofructokinase from euthermic and hibernating Jaculus orientalis. Purification and determination of the quaternary structure.

1. The structural properties of skeletal muscle phosphofructokinase from euthermic and hibernating jerboa were compared. 2. The enzyme was purified by a rapid procedure; suspended in ammonium sulfate in the presence of ATP, it was found to be stable for three weeks. 3. A specific activity of 76 U/mg and at most 65 U/mg was obtained for the enzyme from the euthermic and hibernating jerboa, respectively. 4. The molecular weight was estimated to be 320 kDa for the oligomer and 80 kDa for the subunit. 5. A unique alanine residue was found at the C-terminal end, suggesting that the enzyme is a tetramer made of four identical subunits. 6. The tetrameric structure of phosphofructokinase was confirmed by using crosslinking with disuccinimidyl esters. 7. The kinetics of formation of the different crosslinked species were found to be in agreement with a model of the tetramer corresponding to a dihedral symmetry with isologuous contacts between protomers. 8. The same molecular characteristics and immunochemical properties were found for the enzyme extracted from the euthermic and hibernating animals.