Computer simulations of enzyme catalysis: finding out what has been optimized by evolution

Area of Science:

• Biochemistry
• Computational Chemistry
• Evolutionary Biology

Background:

• Enzyme catalysis is crucial for biological reactions, but its precise origin remains debated.
• Traditional experimental methods struggle to fully elucidate enzyme catalytic mechanisms.
• Evolutionary constraints play a significant role in shaping enzyme function.

Purpose of the Study:

• To investigate the origin of enzyme catalytic power, considering evolutionary constraints.
• To differentiate between proposed enzyme mechanisms using energy considerations and computer simulations.
• To identify the primary factors contributing to the high catalytic efficiency of enzymes.

Main Methods:

• Analysis of energy contributions to enzyme catalysis.
• Computer simulation studies of enzyme mechanisms.
• Evaluation of experimental data, including mutation studies and kinetic parameters (kcat/kcage).

Main Results:

• Standard solution-phase catalysis methods are not employed by enzymes.
• The desolvation hypothesis and ground-state destabilization mechanisms are inconsistent with experimental data.
• Computer simulations highlight electrostatic effects as the dominant catalytic contribution.
• Enzymes possess a preorganized dipolar environment that stabilizes transition states without incurring reorganization energy costs.

Conclusions:

• Enzyme catalytic power originates from electrostatic stabilization of transition states.
• This stabilization is facilitated by a preorganized polar environment, a product of protein folding energy.
• Understanding enzyme catalysis requires integrating experimental data with computational approaches.