Enzyme mechanisms from molecular modeling and isotope effects

Area of Science:

• Biochemistry
• Computational Chemistry
• Enzyme Kinetics

Background:

• Enzyme catalysis mechanisms are complex and require advanced analytical techniques.
• Kinetic isotope effects (KIEs) and molecular modeling are powerful tools for mechanistic investigations.
• Understanding enzyme function is crucial for biochemistry and drug development.

Purpose of the Study:

• To characterize three distinct enzyme-catalyzed reactions using integrated computational and experimental approaches.
• To elucidate the reaction mechanisms of chloroacid dehalogenase, methylmalonyl-CoA mutase, and trihydroxynaphthalene reductase.
• To validate and improve computational methodologies for enzyme mechanism studies.

Main Methods:

• Application of chlorine and solvent kinetic isotope effects to study chloroacid dehalogenase.
• Utilizing Quantum Mechanics/Molecular Mechanics (QM/MM) schemes to investigate the pre-steady-state phase of methylmalonyl-CoA mutase.
• Validation of QM/MM results using experimental deuterium kinetic isotope effects.
• Development and illustration of a procedure for enhancing QM/MM calculations on trihydroxynaphthalene reductase.

Main Results:

• Chlorine and solvent KIEs provided insights into the chloroacid dehalogenase mechanism.
• QM/MM simulations successfully approached the pre-steady-state kinetics of methylmalonyl-CoA mutase.
• Experimental deuterium KIEs validated the computational models for methylmalonyl-CoA mutase.
• A refined QM/MM procedure was demonstrated for analyzing the trihydroxynaphthalene reductase reaction.

Conclusions:

• The combined use of KIEs and molecular modeling is effective for characterizing enzyme mechanisms.
• QM/MM methods, when validated, offer reliable insights into enzyme reaction pathways.
• The study contributes to a deeper understanding of enzymatic reactions and computational chemistry techniques.