2G6M

Structure of rat nNOS heme domain (BH4 bound) complexed with CO

Summary for 2G6M

• Entry DOI: 10.2210/pdb2g6m/pdb
• Descriptor: Nitric-oxide synthase, brain, ACETATE ION, ZINC ION, ... (8 entities in total)
• Functional Keywords: nitric oxide synthase, heme protein, diatomic ligand, oxidoreductase
• Biological source: Rattus norvegicus (Norway rat)
• Cellular location: Cell membrane, sarcolemma; Peripheral membrane protein (By similarity): P29476
• Total number of polymer chains: 2
• Total formula weight: 99529.94

Authors

Li, H.,Igarashi, J.,Jamal, J.,Yang, W.,Poulos, T.L. (deposition date: 2006-02-24, release date: 2006-08-08, Last modification date: 2023-08-30)

Primary citation

Li, H.,Igarashi, J.,Jamal, J.,Yang, W.,Poulos, T.L.
Structural studies of constitutive nitric oxide synthases with diatomic ligands bound.
J.Biol.Inorg.Chem., 11:753-768, 2006

PubMed Abstract: Crystal structures are reported for the endothelial nitric oxide synthase (eNOS)-arginine-CO ternary complex as well as the neuronal nitric oxide synthase (nNOS) heme domain complexed with L: -arginine and diatomic ligands, CO or NO, in the presence of the native cofactor, tetrahydrobiopterin, or its oxidized analogs, dihydrobiopterin and 4-aminobiopterin. The nature of the biopterin has no influence on the diatomic ligand binding. The binding geometries of diatomic ligands to nitric oxide synthase (NOS) follow the {MXY}(n) formalism developed from the inorganic diatomic-metal complexes. The structures reveal some subtle structural differences between eNOS and nNOS when CO is bound to the heme which correlate well with the differences in CO stretching frequencies observed by resonance Raman techniques. The detailed hydrogen-bonding geometries depicted in the active site of nNOS structures indicate that it is the ordered active-site water molecule rather than the substrate itself that would most likely serve as a direct proton donor to the diatomic ligands (CO, NO, as well as O(2)) bound to the heme. This has important implications for the oxygen activation mechanism critical to NOS catalysis.

PubMed: 16804678
DOI: 10.1007/s00775-006-0123-8

Experimental method

X-RAY DIFFRACTION (1.85 Å)