Nitric Oxide Synthase: Difference between revisions

The binding domains of Heme and H4B, as already mentioned,creates a cavity which runs through the monomer. Arginine/Citruline diffuses through this cavity. In the closed conformation, the cavity is so small that only a water molecule can pass. The heme group in the cavity is held in place by van der Waals interactions with the hydrophobic and aliphatic part of the side chains of the protein making up the cavity. The heme has its propionate groups facing the interface.The propionic acid groups of heme forms several hydrogen bonds with water molecules inside the cavity. One of these groups hydrogenbonds to H4B. The iron in heme in pentacoordinated. <ref>PMID: 10074942</ref>