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. 1974 Sep;71(9):3355–3358. doi: 10.1073/pnas.71.9.3355

On the Mechanism of Action of Choline Acetyltransferase

Stephen F Currier 1, Henry G Mautner 1
PMCID: PMC433770  PMID: 4530306

Abstract

The substrate specificity of choline acetyltransferase (EC 2.3.1.6) isolated from squid ganglia was investigated. The enzyme catalyzed the acetylation of choline and aminocholine but not of homocholine. In D2O solution there was considerable slowing of the transacetylation reaction. Photo-oxidation in the presence of methylene blue or rose bengal rapidly inactivated the enzyme, suggesting involvement of a histidine residue in the catalytic site. It seems likely that general-base catalysis by imidazole enhances the ability of enzyme-bound choline (or ammoniumcholine) to react with a thiolester group. Attempts to isolate an acetylthio-enzyme intermediate after incubation with [14C]acetylcoenzyme A were unsuccessful. A possible mechanism for the action of choline acetyltransferase is proposed.

Keywords: substrate specificity, D2O isotope effect, photo-oxidation

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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