ATP-catalyzed preconditioning of phosphofructokinase

Area of Science:

• Biochemistry
• Enzymology
• Protein conformational dynamics

Background:

• Phosphofructokinase (EC 2.7.1.11) exhibits pH-dependent inactivation and reactivation, transitioning between immature and mature conformational states.
• Ligands, including adenosine triphosphate (ATP), are known to facilitate the reactivation process, termed preconditioning.

Purpose of the Study:

• To investigate the catalytic role of ATP in the reactivation and preconditioning of phosphofructokinase.
• To explore the mechanism by which ATP influences enzyme conformation and refolding.

Main Methods:

• Enzyme activity assays under varying pH conditions.
• Investigation of ATP's requirement for maintaining the reactivated enzyme state.
• Experimental conditions designed to observe ATP's catalytic role in both activation and inactivation.

Main Results:

• ATP's continued presence is not necessary to sustain the reactivated state of phosphofructokinase, indicating a catalytic function.
• Conditions were identified where ATP catalyzes both the activation and inactivation of the enzyme.
• ATP enhances both the rate and extent of phosphofructokinase reactivation, promoting correct refolding over inactive species formation.

Conclusions:

• ATP functions catalytically in the reactivation of phosphofructokinase, supporting the concept of small molecules inducing macromolecular conformational changes.
• The preconditioning process mediated by ATP leads to an irreversible commitment to the mature, reactivated enzyme conformation.