PDBsum entry: 1dww

Oxidoreductase/transferase

PDB id: 1dww

Contents

Protein chains

420 a.a. *

Ligands

HEM ×2

H2B ×2

SO4 ×8

HAR ×2

Metals

_ZN ×2

Waters ×691

* Residue conservation analysis

PDB id:

1dww

Name:

Oxidoreductase/transferase

Title:

Murine inducible nitric oxide synthase oxygenase dimer n-hydroxyarginine and dihydrobiopterin

Structure:

Nitric oxide synthase. Chain: a, b. Fragment: oxygenase domain 65-498. Synonym: inducible nos type ii, mac-nos. Engineered: yes. Other_details: murine inducible

Source:

Mus musculus. Mouse. Organism_taxid: 10090. Cell: macrophage. Plasmid: pcwori. Expressed in: escherichia coli. Expression_system_taxid: 562.

Biol. unit:

Dimer (from PDB file)

Resolution:

2.35Å R-factor: 0.249 R-free: 0.288

Authors:

B.R.Crane,A.S.Arvai,E.D.Getzoff,D.J.Stuehr,J.A.Tainer

Key ref:

B.R.Crane et al. (2000). Structures of the N(omega)-hydroxy-L-arginine complex of inducible nitric oxide synthase oxygenase dimer with active and inactive pterins. Biochemistry, 39, 4608-4621. PubMed id: 10769116 DOI: 10.1021/bi992409a

Date:

14-Dec-99 Release date: 06-Feb-00

Protein chains

P29477  (NOS2_MOUSE) -  Nitric oxide synthase, inducible

Seq: 1144 a.a.

Struc: 420 a.a.

Enzyme reactions

• Enzyme class: E.C.1.14.13.39 - Nitric-oxide synthase.
• Reaction: L-arginine + n NADPH + n H⁺ + m O₂ = citrulline + nitric oxide + n NADP⁺

L-arginine (Bound ligand (Het Group name = HAR) matches with 92.00% similarity) + n NADPH + n H(+) + m O(2) = citrulline + nitric oxide + n NADP(+)

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

 Gene Ontology (GO) functional annotation 

• Biological process: oxidation-reduction process (2 terms)
• Biochemical function: calmodulin binding (7 terms)

reference

DOI no: 10.1021/bi992409a

Biochemistry 39:4608-4621 (2000)

PubMed id: 10769116

Structures of the N(omega)-hydroxy-L-arginine complex of inducible nitric oxide synthase oxygenase dimer with active and inactive pterins.

B.R.Crane, A.S.Arvai, S.Ghosh, E.D.Getzoff, D.J.Stuehr, J.A.Tainer.

ABSTRACT

Nitric oxide synthases (NOSs) catalyze two mechanistically distinct, tetrahydrobiopterin (H(4)B)-dependent, heme-based oxidations that first convert L-arginine (L-Arg) to N(omega)-hydroxy-L-arginine (NHA) and then NHA to L-citrulline and nitric oxide. Structures of the murine inducible NOS oxygenase domain (iNOS(ox)) complexed with NHA indicate that NHA and L-Arg both bind with the same conformation adjacent to the heme iron and neither interacts directly with it nor with H(4)B. Steric restriction of dioxygen binding to the heme in the NHA complex suggests either small conformational adjustments in the ternary complex or a concerted reaction of dioxygen with NHA and the heme iron. Interactions of the NHA hydroxyl with active center beta-structure and the heme ring polarize and distort the hydroxyguanidinium to increase substrate reactivity. Steric constraints in the active center rule against superoxo-iron accepting a hydrogen atom from the NHA hydroxyl in their initial reaction, but support an Fe(III)-peroxo-NHA radical conjugate as an intermediate. However, our structures do not exclude an oxo-iron intermediate participating in either L-Arg or NHA oxidation. Identical binding modes for active H(4)B, the inactive quinonoid-dihydrobiopterin (q-H(2)B), and inactive 4-amino-H(4)B indicate that conformational differences cannot explain pterin inactivity. Different redox and/or protonation states of q-H(2)B and 4-amino-H(4)B relative to H(4)B likely affect their ability to electronically influence the heme and/or undergo redox reactions during NOS catalysis. On the basis of these structures, we propose a testable mechanism where neutral H(4)B transfers both an electron and a 3,4-amide proton to the heme during the first step of NO synthesis.