1IRC

CYSTEINE RICH INTESTINAL PROTEIN


Experimental Data Snapshot

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

wwPDB Validation   3D Report Full Report


This is version 1.4 of the entry. See complete history


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

  • DOI: https://doi.org/10.1021/bi00187a023
  • Primary Citation of Related Structures:  
    1IRC

  • 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.


  • Organizational Affiliation

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


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
MYOGLOBIN (METAQUO)154Physeter catodonMutation(s): 1 
Gene Names: SPERM WHALE MYOGLOBIN SYNTHETI
UniProt
Find proteins for P02185 (Physeter macrocephalus)
Explore P02185 
Go to UniProtKB:  P02185
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP02185
Sequence Annotations
Expand
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
HEM
Query on HEM

Download Ideal Coordinates CCD File 
B [auth A]PROTOPORPHYRIN IX CONTAINING FE
C34 H32 Fe N4 O4
KABFMIBPWCXCRK-RGGAHWMASA-L
IMD
Query on IMD

Download Ideal Coordinates CCD File 
C [auth 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 = 40.15α = 90
b = 49.04β = 90
c = 79.14γ = 90
Software Package:
Software NamePurpose
TNTrefinement
SDMSdata reduction

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1996-07-11
    Type: Initial release
  • Version 1.1: 2008-03-24
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2021-11-03
    Changes: Database references, Derived calculations, Other
  • Version 1.4: 2024-02-07
    Changes: Data collection