3ZLV

Crystal structure of mouse acetylcholinesterase in complex with tabun and HI-6


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.5 Å
  • R-Value Free: 0.226 
  • R-Value Work: 0.176 

wwPDB Validation 3D Report Full Report


This is version 1.4 of the entry. See complete history

Literature

Catalytic-Site Conformational Equilibrium in Nerve-Agent Adducts of Acetylcholinesterase; Possible Implications for the Hi-6 Antidote Substrate Specificity.

Artursson, E.Andersson, P.O.Akfur, C.Linusson, A.Borjegren, S.Ekstrom, F.

(2013) Biochem.Pharmacol. 85: 1389

  • DOI: 10.1016/j.bcp.2013.01.016
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Nerve agents such as tabun, cyclosarin and Russian VX inhibit the essential enzyme acetylcholinesterase (AChE) by organophosphorylating the catalytic serine residue. Nucleophiles, such as oximes, are used as antidotes as they can reactivate and resto ...

    Nerve agents such as tabun, cyclosarin and Russian VX inhibit the essential enzyme acetylcholinesterase (AChE) by organophosphorylating the catalytic serine residue. Nucleophiles, such as oximes, are used as antidotes as they can reactivate and restore the function of the inhibited enzyme. The oxime HI-6 shows a notably low activity on tabun adducts but can effectively reactivate adducts of cyclosarin and Russian VX. To examine the structural basis for the pronounced substrate specificity of HI-6, we determined the binary crystal structures of Mus musculus AChE (mAChE) conjugated by cyclosarin and Russian VX and found a conformational mobility of the side chains of Phe338 and His447. The interaction between HI-6 and tabun-adducts of AChE were subsequently investigated using a combination of time resolved fluorescence spectroscopy and X-ray crystallography. Our findings show that HI-6 binds to tabun inhibited Homo sapiens AChE (hAChE) with an IC50 value of 300μM and suggest that the reactive nucleophilic moiety of HI-6 is excluded from the phosphorus atom of tabun. We propose that a conformational mobility of the side-chains of Phe338 and His447 is a common feature in nerve-agent adducts of AChE. We also suggest that the conformational mobility allow HI-6 to reactivate conjugates of cyclosarin and Russian VX while a reduced mobility in tabun conjugated AChE results in steric hindrance that prevents efficient reactivation.


    Organizational Affiliation

    Swedish Defence Research Agency, CBRN, Defence and Security, Umeå, Sweden.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
ACETYLCHOLINESTERASE
A, B
543Mus musculusMutation(s): 0 
Gene Names: Ache
EC: 3.1.1.7
Find proteins for P21836 (Mus musculus)
Go to UniProtKB:  P21836
Small Molecules
Ligands 4 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
PE4
Query on PE4

Download SDF File 
Download CCD File 
B
2-{2-[2-(2-{2-[2-(2-ETHOXY-ETHOXY)-ETHOXY]-ETHOXY}-ETHOXY)-ETHOXY]-ETHOXY}-ETHANOL
POLYETHYLENE GLYCOL PEG4000
C16 H34 O8
PJWQOENWHPEPKI-UHFFFAOYSA-N
 Ligand Interaction
HI6
Query on HI6

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Download CCD File 
A, B
4-(AMINOCARBONYL)-1-[({2-[(E)-(HYDROXYIMINO)METHYL]PYRIDINIUM-1-YL}METHOXY)METHYL]PYRIDINIUM
1-(2-HYDROXY-IMINOMETHYLPYRIDINIUM)-1-(4-CARBOXYAMINO)-PYRIDINIUM DIMETHYLETHER
C14 H16 N4 O3
FJZDLOMCEPUCII-UHFFFAOYSA-P
 Ligand Interaction
CO3
Query on CO3

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Download CCD File 
A
CARBONATE ION
C O3
BVKZGUZCCUSVTD-UHFFFAOYSA-L
 Ligand Interaction
1KA
Query on 1KA

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Download CCD File 
A, B
(2-hydroxyethoxy)acetaldehyde
C4 H8 O3
DSGGHBUAHUMMHN-UHFFFAOYSA-N
 Ligand Interaction
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
SUN
Query on SUN
A, B
L-PEPTIDE LINKINGC7 H17 N2 O5 PSER
External Ligand Annotations 
IDBinding Affinity (Sequence Identity %)
HI6Kd: 27000 - 93000 nM (88) BINDINGDB
HI6IC50: 1360000 nM (88) BINDINGDB
HI6IC50: 300000 nM PDBBIND
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.5 Å
  • R-Value Free: 0.226 
  • R-Value Work: 0.176 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 79.570α = 90.00
b = 112.380β = 90.00
c = 226.990γ = 90.00
Software Package:
Software NamePurpose
REFMACphasing
SCALAdata scaling
XDSdata reduction
PHENIXrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2013-03-27
    Type: Initial release
  • Version 1.1: 2013-08-07
    Type: Database references
  • Version 1.2: 2013-08-14
    Type: Atomic model
  • Version 1.3: 2015-04-01
    Type: Data collection
  • Version 1.4: 2018-01-17
    Type: Data collection