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Updated: Jun 25, 2026
08:32
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
Role of substrate functional groups in binding to nitric oxide synthase
Baochen Fan1, Dennis J Stuehr, Denis L Rousseau
1Department of Physiology and Biophysics, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, NY 10461, USA.
Biochemical and Biophysical Research Communications
|March 3, 2009
Summary
Nitric oxide synthase (NOS) substrate interactions were studied using resonance Raman spectroscopy. An unmodified amino acid end is crucial for catalysis, involving a hydrogen-bonding network.
Area of Science:
- Biochemistry
- Enzymology
- Spectroscopy
Background:
- Nitric oxide synthase (NOS) is a crucial enzyme in biological systems.
- Understanding substrate interactions with the heme CO ligand is key to elucidating NOS function.
- Resonance Raman spectroscopy provides insights into enzyme-ligand dynamics.
Purpose of the Study:
- To investigate the interactions between the heme CO ligand in NOS and various substrate analogues.
- To determine how modifications in substrate functional units affect these interactions.
- To identify key structural features required for NOS catalysis.
Main Methods:
- Resonance Raman spectroscopy was employed to measure Fe-C-O vibrational modes.
- Substrate analogues with varied guanidino groups, amino acid sites, and methylene units were synthesized and tested.
- Spectra were analyzed to observe shifts in Fe-CO stretching and Fe-C-O bending frequencies.
Main Results:
- Interactions between substrate analogues and the heme CO moiety caused shifts in Fe-CO stretching and Fe-C-O bending frequencies, attributed to electrostatic environment changes.
- An unmodified guanidino group showed similar interaction patterns regardless of modifications at the amino acid end.
- An unmodified amino acid end was found to be essential for catalysis.
Conclusions:
- The electrostatic environment significantly influences the interaction between NOS heme CO and substrate analogues.
- Catalysis by NOS is dependent on an intact H-bonding network involving the substrate, heme, and pterin cofactor.
- Specific structural features of the substrate, particularly the amino acid end, are critical for enzyme activity.
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