Crystal structure of human liver carboxylesterase 1 (hCE1) in covalent complex with the nerve agent Cyclosarin (GF)

Experimental Data Snapshot

  • Resolution: 3.10 Å
  • R-Value Free: 0.299 
  • R-Value Work: 0.266 
  • R-Value Observed: 0.270 

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Human carboxylesterase 1 stereoselectively binds the nerve agent cyclosarin and spontaneously hydrolyzes the nerve agent sarin.

Hemmert, A.C.Otto, T.C.Wierdl, M.Edwards, C.C.Fleming, C.D.MacDonald, M.Cashman, J.R.Potter, P.M.Cerasoli, D.M.Redinbo, M.R.

(2010) Mol Pharmacol 77: 508-516

  • DOI: https://doi.org/10.1124/mol.109.062356
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Organophosphorus (OP) nerve agents are potent toxins that inhibit cholinesterases and produce a rapid and lethal cholinergic crisis. Development of protein-based therapeutics is being pursued with the goal of preventing nerve agent toxicity and protecting against the long-term side effects of these agents. The drug-metabolizing enzyme human carboxylesterase 1 (hCE1) is a candidate protein-based therapeutic because of its similarity in structure and function to the cholinesterase targets of nerve agent poisoning. However, the ability of wild-type hCE1 to process the G-type nerve agents sarin and cyclosarin has not been determined. We report the crystal structure of hCE1 in complex with the nerve agent cyclosarin. We further use stereoselective nerve agent analogs to establish that hCE1 exhibits a 1700- and 2900-fold preference for the P(R) enantiomers of analogs of soman and cyclosarin, respectively, and a 5-fold preference for the P(S) isomer of a sarin analog. Finally, we show that for enzyme inhibited by racemic mixtures of bona fide nerve agents, hCE1 spontaneously reactivates in the presence of sarin but not soman or cyclosarin. The addition of the neutral oxime 2,3-butanedione monoxime increases the rate of reactivation of hCE1 from sarin inhibition by more than 60-fold but has no effect on reactivation with the other agents examined. Taken together, these data demonstrate that hCE1 is only reactivated after inhibition with the more toxic P(S) isomer of sarin. These results provide important insights toward the long-term goal of designing novel forms of hCE1 to act as protein-based therapeutics for nerve agent detoxification.

  • Organizational Affiliation

    Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3290, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Liver carboxylesterase 1
A, B, C
529Homo sapiensMutation(s): 0 
Gene Names: CES1CES2SES1
UniProt & NIH Common Fund Data Resources
Find proteins for P23141 (Homo sapiens)
Explore P23141 
Go to UniProtKB:  P23141
PHAROS:  P23141
GTEx:  ENSG00000198848 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP23141
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 3.10 Å
  • R-Value Free: 0.299 
  • R-Value Work: 0.266 
  • R-Value Observed: 0.270 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 55.61α = 90
b = 179.88β = 90
c = 200.06γ = 90
Software Package:
Software NamePurpose
XSCALEdata scaling
PDB_EXTRACTdata extraction
XDSdata scaling
XDSdata reduction

Structure Validation

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Ligand Structure Quality Assessment 

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2010-01-19
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2023-09-06
    Changes: Data collection, Database references, Derived calculations, Refinement description