Acetylation of amines and alcohols catalyzed by acetylcholinesterase from Pseudomonas aeruginosa PAO1

Acetylcholinesterase (AChE) from Pseudomonas aeruginosa PAO1 has a catalytic Ser residue in its active site. In this study, we examined the aminolysis and alcoholysis reactions of AChE that occurred alongside its hydrolysis reaction. The recombinant AChE recognized ethyl acetate as a substrate. Therefore, we evaluated acetylation of the amine and hydroxyl group by AChE, using acetylcholine and ethyl acetate as the acetyl donor. AChE recognized diaminoalkanes with 4-to 12-carbon chains and aminoalcohols with 4-to 8-carbon chains as acetyl acceptors, resulting in their acetylated products. In the acetylation of 1,6-diaminohexane, AChE preferentially used ethyl acetate as the acetyl donor above pH 8.0 and the efficiency increased with increasing pH. In contrast, the acetylation of 6-amino-1-hexanol was efficient with acetylcholine as the acetyl donor in the pH range of 4-10. In addition, acetylated 6-amino-1-hexanol was decomposed by AChE. The kinetic study indicated that the acetyl donor and acceptor are competitively recognized by AChE as substrates.

Automated summary

In this study, the acetylation reactions of acetylcholinesterase (AChE) were examined using different substrates. AChE was found to recognize ethyl acetate, diaminoalkanes, and aminoalcohols, leading to their acetylated products. The preference of AChE for acetyl donor and acceptor varied with pH, with ethyl acetate being preferred at alkaline pH and acetylcholine being preferred at acidic pH. Additionally, acetylated 6-amino-1-hexanol was decomposed by AChE.