期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1974
卷号：71
期号：9
页码：3355-3358
DOI：10.1073/pnas.71.9.3355
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：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.
