Mapping the reaction coordinates of enzymatic defluorination

Area of Science:

• Biochemistry
• Structural Biology
• Enzymology

Background:

• The carbon-fluorine bond is exceptionally strong, making its cleavage challenging.
• Fluoroacetate dehalogenases are rare enzymes capable of hydrolyzing this bond under physiological conditions.
• Understanding the mechanism of C-F bond hydrolysis is key to developing new biocatalysts.

Purpose of the Study:

• To elucidate the molecular basis of fluoroacetate dehalogenase activity.
• To capture structural snapshots of the defluorination reaction mechanism.
• To identify key features enabling enzymatic C-F bond cleavage.

Main Methods:

• High-resolution X-ray crystallography (1.15-1.80 Å).
• Structure determination of enzyme states: free, Michaelis complex, covalent intermediate, and product complex.
• Analysis of active site features and enzyme-product interactions.

Main Results:

• Crystal structures revealed a halide pocket with three hydrogen bonds stabilizing the fluoride ion.
• The active site is tailored for the small fluorine atom, conferring selectivity for fluorinated substrates.
• Enzyme dynamics near the active site were identified as potentially important for catalysis.

Conclusions:

• Enzymatic defluorination relies on a precisely structured active site and specific enzyme dynamics.
• These findings provide fundamental insights into breaking the robust carbon-fluorine bond.
• The study paves the way for designing novel defluorinases for organofluorine biotransformation.