3HSN

Ternary structure of neuronal nitric oxide synthase with NHA and CO bound

Summary for 3HSN

• Entry DOI: 10.2210/pdb3hsn/pdb
• Related: 3HSO 3HSP
• Descriptor: Nitric oxide synthase, brain, PROTOPORPHYRIN IX CONTAINING FE, CARBON MONOXIDE, ... (9 entities in total)
• Functional Keywords: nitric oxide synthase, heme enzyme, diatomic ligand, calmodulin-binding, cell membrane, cell projection, fad, fmn, heme, iron, membrane, metal-binding, nadp, oxidoreductase
• Biological source: Rattus norvegicus (rat)
• Total number of polymer chains: 2
• Total formula weight: 100605.10

Authors

Doukov, T.,Li, H.,Soltis, M.,Poulos, T.L. (deposition date: 2009-06-10, release date: 2009-10-20, Last modification date: 2023-09-06)

Primary citation

Doukov, T.,Li, H.,Soltis, M.,Poulos, T.L.
Single crystal structural and absorption spectral characterizations of nitric oxide synthase complexed with N(omega)-hydroxy-L-arginine and diatomic ligands.
Biochemistry, 48:10246-10254, 2009

PubMed Abstract: The X-ray structures of neuronal nitric oxide synthase (nNOS) with N(omega)-hydroxy-l-arginine (l-NHA) and CO (or NO) bound have been determined at 1.91-2.2 A resolution. Microspectrophotometric techniques confirmed reduced redox state and the status of diatomic ligand complexes during X-ray diffraction data collection. The structure of nNOS-NHA-NO, a close mimic to the dioxygen complex, provides a picture of the potential interactions between the heme-bound diatomic ligand, substrate l-NHA, and the surrounding protein and solvent structure environment. The OH group of l-NHA in the X-ray structures deviates from the plane of the guanidinium moiety substantially, indicating that the OH-bearing, protonated guanidine N(omega) nitrogen of l-NHA has substantial sp(3) hybridization character. This nitrogen geometry, different from that of the guanidinium N(omega) nitrogen of l-arginine, allows a hydrogen bond to be donated to the proximal oxygen of the heme-bound dioxygen complex, thus preventing cleavage of the O-O bond. Instead, it favors the stabilization of the ferric-hydroperoxy intermediate, Fe(3+)-OOH(-), which serves as the active oxidant in the conversion of l-NHA to NO and citrulline in the second reaction of the NOS.

PubMed: 19791770
DOI: 10.1021/bi9009743

Experimental method

X-RAY DIFFRACTION (1.91 Å)