Oxygenase Domain of NOS

NOS is homodimeric with each monomer containing a N-terminal oxygenase domain and a C-terminal reductase domain. The N-terminal oxygenase domain, shown here, contains binding sites for the catalytic heme, tetrahydrobiopterin (H4B), and the substrates L-arginine and molecular oxygen.


This view shows the two monomers of Human Endothelial NOS. One is shown in cyan while the other is shown in dark cyan.

This shows the bounded cofactors and coenzymes. Heme is shown in cpk coloring and there is a tetrahydrobiopterin, the arginine substrate, and a zinc tetrathiolate centre located at the interface between the two monomers. 

This shows one monomer. Although each monomer folds as a single domain, it is helpful to describe the structure in terms of the 3 domains shown.


Nat Struct Biol. 1999 Mar;6(3):233-42.
Structural characterization of nitric oxide synthase isoforms reveals striking active-site conservation.
Fischmann TO1, Hruza A, Niu XD, Fossetta JD, Lunn CA, Dolphin E, Prongay AJ, Reichert P, Lundell DJ, Narula SK, Weber PC. PubMed

3NOS(PDB)

Table of Contents 

Back            Next