Question

What are the substrates and products of the nitric oxide synthase reaction?

Short answer

The reaction that converts arginine to$\text{NO}$ and citrulline is catalyzed by nitric oxide synthase (NOS).

Step-by-step solution

 Endothelium-derived relaxing factor (EDRF).  

Arginine is the precursor of an endothelium-derived relaxing factor (EDRF) substance because it was synthesized by vascular endothelial cells and caused the underlying smooth muscle to relax.

 Enzyme-bound hydroxyarginine.  

The reaction proceeds via an enzyme-bound hydroxyarginine intermediate and requires an array of redox coenzymes. NOS is a homodimeric protein of 125-to 160-kD subunits, and each subunit contains one FMN, one FAD, one tetrahydrobiopterin, and one Fe(III)-heme. These cofactors facilitate the five-electron oxidation of arginine produce $\mathrm{NO}$.