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Updated: Mar 15, 2026
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Application of Genetically Encoded Fluorescent Nitric Oxide (NO•) Probes, the geNOps, for Real-time Imaging of NO• Signals in Single Cells
Published on: March 16, 2017
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Domain interactions in neuronal nitric oxide synthase identified by time-resolved fluorescence
Alexa A Snyder1, Christian L McCoy1, Alexandria K Gambill1
1Department of Chemistry, University of Kansas, Lawrence, Kansas.
Biophysical Journal
|March 14, 2026
Summary
Nitric oxide synthase (NOS) activity relies on conformational changes. Calmodulin (CaM) binding to NOS induces states that facilitate electron transfer, crucial for nitric oxide production.
Area of Science:
- Biochemistry
- Molecular Biology
- Enzyme kinetics
Background:
- Nitric oxide synthase (NOS) produces nitric oxide (NO) via electron transfer.
- Calmodulin (CaM) regulates NOS activity by binding to a specific domain.
- Electron transfer in NOS is thought to be conformationally gated.
Purpose of the Study:
- To investigate the conformational states of NOS during electron transfer.
- To understand the role of CaM in regulating NOS conformational dynamics.
- To correlate enzyme conformations with electron transfer efficiency.
Main Methods:
- Utilized fluorescence-labeled CaM and time-resolved fluorescence detection.
- Employed Förster Resonance Energy Transfer (FRET) to monitor CaM-heme proximity.
- Analyzed fluorescence decays from site-directed mutants of NOS and CaM.
Main Results:
- Identified multiple conformational states of NOS using fluorescence techniques.
- Demonstrated that FRET efficiency is dependent on the enzyme's conformational state.
- Mutational analysis assigned specific conformations to interactions between enzyme domains and CaM.
Conclusions:
- NOS exists in distinct conformational states that gate electron transfer.
- CaM binding to the oxygenase domain is critical for productive FMN-heme interaction.
- These findings elucidate the mechanism of conformationally controlled electron transfer in NOS.
