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Updated: Aug 9, 2026

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Monitoring the Reductive and Oxidative Half-Reactions of a Flavin-Dependent Monooxygenase using Stopped-Flow Spectrophotometry
Published on: March 18, 2012
Monomeric sarcosine oxidase: 1. Flavin reactivity and active site binding determinants
M A Wagner1, P Trickey, Z W Chen
1Department of Biochemistry, MCP Hahnemann School of Medicine, Philadelphia, Pennsylvania 19129, USA.
Biochemistry
|July 29, 2000
Summary
Monomeric sarcosine oxidase (MSOX) stabilizes flavin forms and binds substrates through specific interactions. Understanding these properties aids in designing MSOX inhibitors and related enzyme therapeutics.
Area of Science:
- Biochemistry
- Enzymology
- Structural Biology
Background:
- Monomeric sarcosine oxidase (MSOX) is a bacterial flavoenzyme catalyzing sarcosine oxidative demethylation.
- It features covalently bound flavin adenine dinucleotide (FAD) [8alpha-(S-cysteinyl)FAD].
Purpose of the Study:
- To characterize the spectroscopic and thermodynamic properties of MSOX.
- To elucidate enzyme-inhibitor interactions through X-ray crystallography.
- To identify key binding determinants for substrate analogs.
Main Methods:
- Spectroscopic analysis (UV-Vis absorption).
- Thermodynamic binding studies with substrate analogs.
- X-ray crystallography of enzyme-inhibitor complexes.
Main Results:
- MSOX stabilizes the anionic oxidized flavin (pKa=8.3) and flavin radical (pKa<6).
- Sarcosine's carboxyl group is essential for binding; amino group substitution impacts affinity via donor-pi interactions.
- Charge-transfer complexes form with sulfur, selenium, or tellurium-containing ligands, correlating with redox potentials.
Conclusions:
- MSOX exhibits unique flavin stabilization properties.
- Binding interactions are sensitive to heteroatom identity and position, influencing affinity and charge-transfer complex formation.
- Structural and thermodynamic data provide insights for MSOX-based inhibitor design.
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