Protein Flexibility and Stiffness Enable Efficient Enzymatic Catalysis.

Area of Science:

• Biochemistry
• Enzyme kinetics
• Protein dynamics

Background:

• Enzyme catalysis relies on stabilizing interactions with reaction transition states.
• Enzymes exhibit higher affinity for transition states than substrates, driving rate accelerations.

Purpose of the Study:

• To investigate how ligand-binding energy drives enzyme conformational changes.
• To generalize findings on enzyme flexibility and activity to various catalytic reactions.

Main Methods:

• Experimental analysis of phosphodianion-binding energy in phosphate monoester substrates.
• Computational modeling of ligand-driven conformational changes in triosephosphate isomerase.

Main Results:

• Substrate binding energy converts flexible enzymes into stiff, active Michaelis complexes.
• Enzyme conformational complexity correlates with increased rate acceleration.
• Flexible enzyme structures, like TIM-barrel folds, evolve to utilize binding energy for conformational changes.

Conclusions:

• Ligand-binding energy is crucial for molding flexible enzymes into catalytically active states.
• This mechanism optimizes the expression of transition-state binding energies, enhancing enzyme specificity.
• Protein dynamics play a significant role in enzyme kinetics and evolution.