Torpedo acetylcholinesterase - Hg heavy-atom derivative

Experimental Data Snapshot

  • Resolution: 2.80 Å
  • R-Value Free: 0.262 
  • R-Value Work: 0.204 
  • R-Value Observed: 0.204 

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This is version 1.4 of the entry. See complete history


A Metastable State of Torpedo Californica Acetylcholinesterase Generated by Modification with Organomercurials

Kreimer, D.I.Dolginova, E.A.Raves, M.Sussman, J.L.Silman, I.Weiner, L.

(1994) Biochemistry 33: 14407

  • DOI: https://doi.org/10.1021/bi00252a006
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Chemical modification of Torpedo californica acetylcholinesterase by various sulfhydryl reagents results in its conversion to one of two principal states. One of these states, viz., that produced by disulfides and alkylating agents, is stable. The second state, produced by mercury derivatives, is metastable. At room temperature, it converts spontaneously, with a half-life of ca. 1 h, to a stable state similar to that produced by the disulfides and alkylating agents. Demodification of acetylcholinesterase freshly modified by mercurials, by its exposure to reduced glutathione, causes rapid release of the bound mercurial, with concomitant recovery of most of the enzymic activity of the native enzyme. In contrast, similar demodification of acetylcholinesterase modified by disulfides yields no detectable recovery of enzymic activity. Spectroscopic measurements, employing CD, intrinsic fluorescence, and binding of 1-anilino-8-naphthalenesulfonate, show that the state produced initially by mercurials is "native-like", whereas that produced by disulfides and alkylating agents, and after prolonged incubation of the mercurial-modified enzyme, is partially unfolded and displays many of the features of the "molten globule" state. Arrhenius plots show that the quasi-native state produced by organomercurials is separated by a low (5 kcal/mol) energy barrier from the native state, whereas the partially unfolded state is separated from the quasi-native state by a high energy barrier (ca. 50 kcal/mol). Comparison of the 3D structures of native acetylcholinesterase and of a heavy-atom derivative obtained with HgAc2 suggests that the mercurial-modified enzyme may be stabilized by additional interactions of the mercury atom attached to the free thiol group of Cys231, specifically with Ser228O gamma with the main-chain nitrogen and carbonyl oxygen of the same serine residue.

  • Organizational Affiliation

    Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
ACETYLCHOLINESTERASE543Tetronarce californicaMutation(s): 0 
Find proteins for P04058 (Tetronarce californica)
Explore P04058 
Go to UniProtKB:  P04058
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP04058
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.80 Å
  • R-Value Free: 0.262 
  • R-Value Work: 0.204 
  • R-Value Observed: 0.204 
  • Space Group: P 31 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 110.7α = 90
b = 110.7β = 90
c = 135γ = 120
Software Package:
Software NamePurpose
XDSdata reduction
XSCALEdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2006-09-05
    Type: Initial release
  • Version 1.1: 2011-05-08
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2021-05-12
    Changes: Derived calculations, Other
  • Version 1.4: 2023-12-13
    Changes: Data collection, Database references, Refinement description