Biological Assembly 1  

 3D View: Structure | Ligand Interaction

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Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Monomer - A 

Biological assembly 1 assigned by authors.

Macromolecule Content

• Total Structure Weight: 17970.63 
• Atom Count: 1216 
• Residue Count: 154 
• Unique protein chains: 1

1IRC

CYSTEINE RICH INTESTINAL PROTEIN

• DOI: 10.2210/pdb1IRC/pdb

• Classification: OXYGEN STORAGE
• Organism(s): Physeter catodon
• Expression System: Escherichia coli
• Mutation(s): 1 


• Deposited: 1995-12-19 Released: 1996-07-11 
• Deposition Author(s): Barrick, D.E., Feese, M.

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.17 Å

Literature

Replacement of the proximal ligand of sperm whale myoglobin with free imidazole in the mutant His-93-->Gly.

Barrick, D.

(1994) Biochemistry 33: 6546-6554

• PubMed: 8204590 


• PubMed Abstract: 
  

The proximal bond between the iron atom of the heme group and the N epsilon of histidine F8 in myoglobin (Mb) and hemoglobin (Hb) is presumed to be an important determinant of heme binding, protein structure, and oxygen binding. Here a system is described in which the proximal ligand is provided intermolecularly by the histidine side chain mimic imidazole. The proximal ligand of sperm whale Mb is replaced with glycine (H93G) using site-directed mutagenesis. The addition of imidazole to Escherichia coli expressing this gene reconstitutes myoglobin function. H93G Mb purified in the presence of imidazole is spectroscopically similar to wild-type Mb in combination with a wide variety of distal ligands. The crystal structure of H93G Mb, determined in the presence of imidazole, reveals that an imidazole molecule is bonded to the heme iron on the proximal side, substituting in trans for the side-chain function of the proximal histidine of wild-type Mb. Although H93G Mb is similar in spectroscopic and gross structural detail to wild-type Mb, subtle differences exist in the orientation of imidazole with respect to the heme group. trans-Complementation of proximal ligand function will allow the proximal bond in hemoproteins to be chemically substituted beyond the limits of the genetic code.

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Related Citations: 

• Replacement of the Proximal Ligand of Sperm Whale Myoglobin with Free Imidazole in the Mutant His-93-->Gly
  Barrick, D.
  (1994) Biochemistry 33: 6546




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Organizational Affiliation: 

Institute of Molecular Biology, University of Oregon, Eugene 97403.

Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details
MYOGLOBIN (METAQUO)	A	154	Physeter catodon	Mutation(s): 1  Gene Names: MB
Find proteins for P02185 (Physeter catodon) Go to Gene View: MB Go to UniProtKB:  P02185

Small Molecules

Ligands 2 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram & Interactions
HEM	A	PROTOPORPHYRIN IX CONTAINING FE HEME C34 H32 Fe N4 O4 KABFMIBPWCXCRK-RGGAHWMASA-L
IMD	A	IMIDAZOLE C3 H5 N2 RAXXELZNTBOGNW-UHFFFAOYSA-O

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.17 Å
• Space Group: P 2₁ 2₁ 2₁

Unit Cell:

Length (Å)	Angle (°)
a = 40.150	α = 90.00
b = 49.040	β = 90.00
c = 79.140	γ = 90.00

Software Package:

Software Name	Purpose
SDMS	data reduction
TNT	refinement

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 1995-12-19 
• Released Date: 1996-07-11 
• Deposition Author(s): Barrick, D.E., Feese, M.

Revision History 

• Version 1.0: 1996-07-11
  Type: Initial release
• Version 1.1: 2008-03-24
  Type: Version format compliance
• Version 1.2: 2011-07-13
  Type: Version format compliance