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Related Experiment Video

Updated: Dec 8, 2025

Expression and Purification of Nuclease-Free Oxygen Scavenger Protocatechuate 3,4-Dioxygenase

Expression and Purification of Nuclease-Free Oxygen Scavenger Protocatechuate 3,4-Dioxygenase

Published on: November 8, 2019

Choline oxidases.

Giovanni Gadda¹

¹Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, United States; Department of Biology, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, United States.

|September 21, 2020

Summary

This summary is machine-generated.

Choline oxidase converts choline to glycine betaine, a vital compatible solute. Mechanistic, structural, and computational studies reveal its detailed molecular action and enzyme dynamics.

Keywords:

Alkoxide Catalytic base Choline oxidase Glycine betaine Hydride transfer quantum tunneling Kinetic isotope effects Oxidase Transition state pH effects

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Area of Science:

Biochemistry
Enzymology
Protein Science

Background:

Choline oxidase is crucial for producing glycine betaine, a compatible solute used by cells to manage osmotic stress.
It serves as a model enzyme for flavoprotein-catalyzed alcohol oxidation.
Understanding its mechanism is vital for medical and biotechnological applications.

Purpose of the Study:

To elucidate the molecular mechanism, structure, and dynamics of choline oxidase from Arthrobacter globiformis.
To identify key amino acid residues and their roles in substrate binding and catalysis.
To explore unique enzymatic phenomena observed in choline oxidase.

Main Methods:

Mechanistic studies
Structural analysis
Computational simulations
Biochemical assays

Main Results:

Detailed elucidation of the four-electron, two-step oxidation mechanism of choline to glycine betaine.
Identification of gated active site access for choline and oxygen.
Characterization of substrate-binding residues and their contributions.
Recognition of the roles of nonpolar side chains and substrate charge in oxygen activation.
Description of phenomena such as photoinduced adducts and bicovalent flavoprotein formation.

Conclusions:

The structure-function-dynamics of choline oxidase are well-understood at the molecular level.
Key catalytic steps involve hydride transfer, an asynchronous transition state, and alkoxide intermediate stabilization.
Enzyme dynamics and unique reactive intermediates are critical for its function.