3DL7

Aged Form of Mouse Acetylcholinesterase Inhibited by Tabun- Update


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.50 Å
  • R-Value Free: 0.227 
  • R-Value Work: 0.187 
  • R-Value Observed: 0.188 

wwPDB Validation   3D Report Full Report


Ligand Structure Quality Assessment 


This is version 1.4 of the entry. See complete history


Literature

Aging of Cholinesterases Phosphylated by Tabun Proceeds through O-Dealkylation.

Carletti, E.Li, H.Li, B.Ekstrom, F.Nicolet, Y.Loiodice, M.Gillon, E.Froment, M.T.Lockridge, O.Schopfer, L.M.Masson, P.Nachon, F.

(2008) J Am Chem Soc 130: 16011-16020

  • DOI: https://doi.org/10.1021/ja804941z
  • Primary Citation of Related Structures:  
    3DJY, 3DKK, 3DL4, 3DL7

  • PubMed Abstract: 

    Human butyrylcholinesterase (hBChE) hydrolyzes or scavenges a wide range of toxic esters, including heroin, cocaine, carbamate pesticides, organophosphorus pesticides, and nerve agents. Organophosphates (OPs) exert their acute toxicity through inhibition of acetylcholinesterase (AChE) by phosphorylation of the catalytic serine. Phosphylated cholinesterase (ChE) can undergo a spontaneous, time-dependent process called "aging", during which the OP-ChE conjugate is dealkylated. This leads to irreversible inhibition of the enzyme. The inhibition of ChEs by tabun and the subsequent aging reaction are of particular interest, because tabun-ChE conjugates display an extraordinary resistance toward most current oxime reactivators. We investigated the structural basis of oxime resistance for phosphoramidated ChE conjugates by determining the crystal structures of the non-aged and aged forms of hBChE inhibited by tabun, and by updating the refinement of non-aged and aged tabun-inhibited mouse AChE (mAChE). Structures for non-aged and aged tabun-hBChE were refined to 2.3 and 2.1 A, respectively. The refined structures of aged ChE conjugates clearly show that the aging reaction proceeds through O-dealkylation of the P(R) enantiomer of tabun. After dealkylation, the negatively charged oxygen forms a strong salt bridge with protonated His438N epsilon2 that prevents reactivation. Mass spectrometric analysis of the aged tabun-inhibited hBChE showed that both the dimethylamine and ethoxy side chains were missing from the phosphorus. Loss of the ethoxy is consistent with the crystallography results. Loss of the dimethylamine is consistent with acid-catalyzed deamidation during the preparation of the aged adduct for mass spectrometry. The reported 3D data will help in the design of new oximes capable of reactivating tabun-ChE conjugates.


  • Organizational Affiliation

    Département de Toxicologie, Centre de Recherches du Service de Santé des Armées, 38700 La Tronche, France.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Acetylcholinesterase
A, B
548Mus musculusMutation(s): 2 
Gene Names: Ache
EC: 3.1.1.7
UniProt & NIH Common Fund Data Resources
Find proteins for P21836 (Mus musculus)
Explore P21836 
Go to UniProtKB:  P21836
IMPC:  MGI:87876
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP21836
Glycosylation
Glycosylation Sites: 1Go to GlyGen: P21836-1
Sequence Annotations
Expand
  • Reference Sequence
Small Molecules
Modified Residues  2 Unique
IDChains TypeFormula2D DiagramParent
SEN
Query on SEN
A, B
L-PEPTIDE LINKINGC5 H13 N2 O5 PSER
SUN
Query on SUN
A, B
L-PEPTIDE LINKINGC7 H17 N2 O5 PSER
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.50 Å
  • R-Value Free: 0.227 
  • R-Value Work: 0.187 
  • R-Value Observed: 0.188 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 79.02α = 90
b = 110.88β = 90
c = 226.38γ = 90
Software Package:
Software NamePurpose
MOLREPphasing
REFMACrefinement
PDB_EXTRACTdata extraction
XDSdata scaling
XDSdata reduction
SCALAdata scaling

Structure Validation

View Full Validation Report



Ligand Structure Quality Assessment 


Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2008-12-02
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Non-polymer description, Version format compliance
  • Version 1.2: 2018-03-07
    Changes: Data collection
  • Version 1.3: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Data collection, Database references, Derived calculations, Structure summary
  • Version 1.4: 2021-03-31
    Changes: Source and taxonomy, Structure summary