Related Experiment Video
Updated: Aug 20, 2026

Monitoring the Reductive and Oxidative Half-Reactions of a Flavin-Dependent Monooxygenase using Stopped-Flow Spectrophotometry
Published on: March 18, 2012
Are the redox properties of tetrahydrofolate cofactors utilized in folate-dependent reactions?
Abstract:
Tetrahydrofolate (H4folate) derivatives are chemically analogous to tetrahydropterins and dihydroflavins, and like these compounds can be oxidized readily. The roles of pterin and flavin cofactors in biological oxidoreductions are well documented. However, with the exception of the reaction catalyzed by thymidylate synthase, explicit oxidoreductions of the H4folate cofactor do not occur in enzyme-catalyzed folate-dependent reactions. We have been studying methylenetetrahydrofolate reductase from pig liver. This enzyme catalyzes the reversible conversion of the exocyclic N5,N10-methylene substituent to an N5-methyl group. Our studies suggest that the detailed mechanism of this reduction of an exocyclic group involves the oxidoreduction of the tetrahydropterin ring system in a manner that is not apparent from the overall reaction stoichiometry. We suggest that such latent oxidoreductions of H4folate cofactors may also occur in other H4folate-dependent reactions, such as the reaction catalyzed by methionine synthase.
Related Concept Videos
Redox Reactions
Role of Reduced Coenzymes NADH and FADH₂
Oxidation and Reduction of Organic Molecules
The removal of an electron from a molecule, results in a...
Oxidation of Phenols to Quinones
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox property is crucial in...
Redox Equilibria: Overview
Redox Reactions

