PDBsum entry: 1twr

Oxidoreductase

PDB id: 1twr

Contents

Protein chains

214 a.a. *

Ligands

VER-_NO ×2

Waters ×193

* Residue conservation analysis

PDB id:

1twr

Name:

Oxidoreductase

Title:

Crystal structures of ferrous and ferrous-no forms of verdoheme in a complex with human heme oxygenase-1: catalytic implications for heme cleavage

Structure:

Heme oxygenase 1. Chain: a, b. Synonym: ho-1. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: hmox1, ho1, ho. Expressed in: escherichia coli. Expression_system_taxid: 562.

Biol. unit:

Dimer (from PQS)

Resolution:

2.10Å R-factor: 0.241

Authors:

L.Lad,P.R.Ortiz De Montellano,T.L.Poulos

Key ref:

L.Lad et al. (2004). Crystal structures of ferrous and ferrous-NO forms of verdoheme in a complex with human heme oxygenase-1: catalytic implications for heme cleavage. J Inorg Biochem, 98, 1686-1695. PubMed id: 15522396 DOI: 10.1016/j.jinorgbio.2004.07.004

Date:

01-Jul-04 Release date: 05-Jul-05

Protein chains

P09601  (HMOX1_HUMAN) -  Heme oxygenase 1

Seq: 288 a.a.

Struc: 215 a.a.

Enzyme reactions

• Enzyme class: E.C.1.14.99.3 - Heme oxygenase.
• Reaction: Heme + 3 AH₂ + 3 O₂ = biliverdin + Fe²⁺ + CO + 3 A + 3 H₂O

Heme + 3 × AH(2) + 3 × O(2) = biliverdin (Bound ligand (Het Group name = VER) matches with 84.00% similarity) + Fe(2+) + CO + 3 × A + 3 × H(2)O

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

 Gene Ontology (GO) functional annotation 

• Biological process: oxidation reduction (2 terms)
• Biochemical function: heme oxygenase (decyclizing) activity (1 term)

reference

DOI no: 10.1016/j.jinorgbio.2004.07.004

J Inorg Biochem 98:1686-1695 (2004)

PubMed id: 15522396

Crystal structures of ferrous and ferrous-NO forms of verdoheme in a complex with human heme oxygenase-1: catalytic implications for heme cleavage.

L.Lad, P.R.Ortiz de Montellano, T.L.Poulos.

ABSTRACT

Heme oxygenase oxidatively degrades heme to biliverdin resulting in the release of iron and CO through a process in which the heme participates both as a cofactor and substrate. One of the least understood steps in the heme degradation pathway is the conversion of verdoheme to biliverdin. In order to obtain a better understanding of this step we report the crystal structures of ferrous-verdoheme and, as a mimic for the oxy-verdoheme complex, ferrous-NO verdoheme in a complex with human HO-1 at 2.20 and 2.10 A, respectively. In both structures the verdoheme occupies the same binding location as heme in heme-HO-1, but rather than being ruffled verdoheme in both sets of structures is flat. Both structures are similar to their heme counterparts except for the distal helix and heme pocket solvent structure. In the ferrous-verdoheme structure the distal helix moves closer to the verdoheme, thus tightening the active site. NO binds to verdoheme in a similar bent conformation to that found in heme-HO-1. The bend angle in the verodoheme-NO structure places the terminal NO oxygen 1 A closer to the alpha-meso oxygen of verdoheme compared to the alpha-meso carbon on the heme-NO structure. A network of water molecules, which provide the required protons to activate the iron-oxy complex of heme-HO-1, is absent in both ferrous-verdoheme and the verdoheme-NO structure.