A “molten globule” of Torpedo acetylcholinesterase undergoes thiol-disulfide exchange

Torpedo acetylcholinesterase is a disulfide-linked homodimer containing three intramolecular disulfide bonds, as well as a single free thiol on Cys-231. We report that in a “molten globule” state, produced by 1.5 M guanidine hydrochloride, this enzyme undergoes rapid intramolecular thiol-disulfide e...

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Bibliographic Details
Published in:The Journal of biological chemistry 1994-12, Vol.269 (48), p.30093-30096
Main Authors: Eichler, J, Kreimer, D.I., Varon, L, Silman, I, Weiner, L
Format: Article
Language:English
Subjects:
Acetylcholinesterase - chemistry
Acetylcholinesterase - isolation & purification
Acetylcholinesterase - metabolism
Animals
Chromatography, Gel
Chromatography, High Pressure Liquid
Disulfides - metabolism
Electric Organ - enzymology
Electrophoresis, Polyacrylamide Gel
Guanidine
Guanidines
Macromolecular Substances
Marine
Protein Conformation
Protein Denaturation
Protein Folding
Sulfhydryl Compounds - metabolism
Torpedo
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Summary:Torpedo acetylcholinesterase is a disulfide-linked homodimer containing three intramolecular disulfide bonds, as well as a single free thiol on Cys-231. We report that in a “molten globule” state, produced by 1.5 M guanidine hydrochloride, this enzyme undergoes rapid intramolecular thiol-disulfide exchange, in the absence of reducing agents, resulting in the production of novel species. Most strikingly, this results in appearance of enzyme monomers. Chemical modification of the free thiol group prevents these changes. Unfolded acetylcholinesterase, namely in 5 M guanidine hydrochloride, also undergoes intramolecular thiol-disulfide exchange, including production of enzyme monomers, but at a much lower rate. Our data show that the molten globule state, in contrast to the native and unfolded states, is both compact and flexible, thus being especially amenable to thiol-disulfide exchange.
ISSN:0021-9258
1083-351X
DOI:10.1016/S0021-9258(18)43778-7