Fructose 6-phosphate prevents the proteolyzed derivative of Escherichia coli phosphofructokinase from dissociation and inactivation.

摘要: N-terminal sequence analysis shows that the limited proteolysis of Escherichia coli phosphofructokinase results in removal 40-50 C-terminal residues each chain. When tetrameric, this proteolyzed derivative is still active albeit insensitive to allosteric effectors (Le Bras, G., and Garel, J.-R. (1982) Biochemistry 21, 6656-6660). In absence fructose 6-phosphate, spontaneously loses its activity dissociates into dimeric species. This inactivation/dissociation slowed down by binding 6-phosphate only part sites; it completely prevented saturation all four sites. The other substrate ATP does not protect against inactivation/dissociation. due denaturation can be reversed some conditions addition 6-phosphate. tetrameric structure stable when either segment removed or sites are occupied.