PDBsum entry 2g6h

Oxidoreductase

PDB id: 2g6h

Contents

Protein chains

407 a.a. *

Ligands

ACT ×2

HEM ×2

H4B ×2

ARG ×2

Metals

_ZN

Waters ×431

* Residue conservation analysis

PDB id:

2g6h

Name:

Oxidoreductase

Title:

Structure of rat nnos heme domain (bh4 bound) in the reduced form

Structure:

Nitric-oxide synthase, brain. Chain: a, b. Synonym: nos type i, neuronal nos, n-nos, nnos, constitutive nos, nc- nos, bnos. Engineered: yes

Source:

Rattus norvegicus. Norway rat. Organism_taxid: 10116. Gene: nos1, bnos. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Biol. unit:

Dimer (from PQS)

Resolution:

2.00Å R-factor: 0.221 R-free: 0.256

Authors:

H.Li,J.Igarashi,J.Jamal,W.Yang,T.L.Poulos

Key ref:

H.Li et al. (2006). Structural studies of constitutive nitric oxide synthases with diatomic ligands bound. J Biol Inorg Chem, 11, 753-768. PubMed id: 16804678

Date:

24-Feb-06 Release date: 08-Aug-06

Protein chains

P29476  (NOS1_RAT) -  Nitric oxide synthase 1 from Rattus norvegicus

Seq: 1429 a.a.

Struc: 407 a.a.

Enzyme reactions

• Enzyme class: E.C.1.14.13.39 - nitric-oxide synthase (NADPH).
• Reaction: 2 L-arginine + 3 NADPH + 4 O2 + H⁺ = 2 L-citrulline + 2 nitric oxide + 3 NADP⁺ + 4 H2O

2 × L-arginine + 3 × NADPH (Bound ligand (Het Group name = ARG) corresponds exactly) + 4 × O2 + H(+) = 2 × L-citrulline + 2 × nitric oxide + 3 × NADP(+) + 4 × H2O

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

J Biol Inorg Chem 11:753-768 (2006)

PubMed id: 16804678

Structural studies of constitutive nitric oxide synthases with diatomic ligands bound.

H.Li, J.Igarashi, J.Jamal, W.Yang, T.L.Poulos.

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.