Research article summary (published 25 Jan 2009):

Stabilization of Torpedo californica acetylcholinesterase by reversible inhibitors.

Full Abstract

The dimeric form of Torpedo californica acetylcholinesterase provides a valuable experimental system for studying transitions between native, partially unfolded, and unfolded states since long-lived partially unfolded states can be generated by chemical modification of a nonconserved buried cysteine residue, Cys 231, by denaturing agents, by oxidative stress, and by thermal inactivation. Elucidation of the 3D structures of complexes of Torpedo californica acetylcholinesterase with a repertoire of reversible inhibitors permits their classification into three categories: (a) active-site directed inhibitors, which interact with the catalytic anionic subsite, at the bottom of the active-site gorge, such as edrophonium and tacrine; (b) peripheral anionic site inhibitors, which interact with a site at the entrance to the gorge, such as propidium and d-tubocurarine; and (c) elongated gorge-spanning inhibitors, which bridge the two sites, such as BW284c51 and decamethonium. The effects of these three categories of reversible inhibitors on the stability of Torpedo californica acetylcholinesterase were investigated using spectroscopic techniques and differential scanning calorimetry. Thermodynamic parameters obtained calorimetrically permitted quantitative comparison of the effects of the inhibitors on the enzyme's thermal stability. Peripheral site inhibitors had a relatively small effect, while gorge-spanning ligands and those binding at the catalytic anionic site, had a much larger stabilizing effect. The strongest effect was, however, observed with the polypeptide toxin, fasciculin II (FasII), even though, in terms of its binding site, it belongs to the category of peripheral site ligands. The stabilizing effect of the ligands binding at the anionic subsite of the active site, like that of the gorge-spanning ligands, may be ascribed to their capacity to stabilize the interaction between the two subdomains of the enzyme. The effect of fasciculin II may be ascribed to the large surface area of interaction (>2000 A(2)) between the two proteins. Stabilization of Torpedo californica acetylcholinesterase by both divalent cations and chemical chaperones was earlier shown to be due to a shift in equilibrium between the native state and a partially unfolded state ( Millard et al. ( 2003 ) Protein Sci. 12 , 2337 - 2347 ). The low molecular weight inhibitors used in the present study may act similarly and can thus be considered as pharmacological chaperones for stabilizing the fully folded native form of the enzyme.

Author information

Author/s: Weiner, Lev (L); Shnyrov, Valery L (VL); Konstantinovskii, Leonid (L); Roth, Esther (E); Ashani, Yacov (Y); Silman, Israel (I);

Affiliation: Chemical Research Support and Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel. Lev.Weiner(-atsign-)weizmann.ac.il

Grants: U54NS058183 (Agency:NINDS NIH HHS)

Journal and publication information

Publication Type: Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.

Journal: Biochemistry (Biochemistry), published in United States. (Language: eng)

Reference: 2009-Jan; vol 48 (issue 3) : pp 563-74

Dates: Created 2009/01/20; Completed 2009/02/04;

PMID: 19115961, status: MEDLINE (last retrieved date: 2/18/2009)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MeSH Headings (categories) shown below.

Acetylcholinesterase - metabolism Animals Benzenaminium, 4,4'-(3-oxo-1,5-pentanediyl)bis(N,N-dimethyl-N-2-propenyl-), Dibromide - pharmacology Calorimetry Cholinesterase Inhibitors - pharmacology Decamethonium Compounds - pharmacology Disulfides - metabolism Elapid Venoms - pharmacology Entropy Enzyme Activation - drug effects Enzyme Stability - drug effects Guanidine - pharmacology

Guanidine - pharmacology Humans Kinetics Ligands Magnetic Resonance Spectroscopy Protein Denaturation - drug effects Protein Folding - drug effects Protein Structure, Secondary Spin Labels Tacrine - pharmacology Temperature Torpedo - metabolism

Note: Bold headings indicate primary MeSH headings or qualifiers.

Associated Chemicals: Cholinesterase Inhibitors (0) ; Decamethonium Compounds (0) ; Disulfides (0) ; Elapid Venoms (0) ; Ligands (0) ; Spin Labels (0) ; Guanidine (113-00-8) ; decamethonium (156-74-1) ; Tacrine (321-64-2) ; Benzenaminium, 4,4'-(3-oxo-1,5-pentanediyl)bis(N,N-dimethyl-N-2-propenyl-), Dibromide (402-40-4) ; fasciculin (86697-68-9) ; Acetylcholinesterase (EC 3.1.1.7)

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