The "neutral" hydrolysis of simple carboxylic esters in water and the rate enhancements produced by acetylcholinesterase and other carboxylic acid esterases.
The "neutral" hydrolysis of simple carboxylic esters in water and the rate enhancements produced by acetylcholinesterase and other carboxylic acid esterases.
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DOI：
10.1021/ja204116a
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发表时间：
2011-08
影响因子：
15
通讯作者：
R. Wolfenden;Yang Yuan
中科院分区：
文献类型：
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作者：
R. Wolfenden;Yang Yuan
在高温下的实验可以确定神经递质乙酰胆碱在水中中性水解的速率常数和热力学激活参数。在25°C时，非催化（或中性）乙酰胆碱水解的外推速率常数为3.9 × 10(-7) s(-1) (ΔH（‡）= 20.0 kcal/mol；TΔS（‡）= -6.1 kcal/mol)。乙酰胆碱比乙酸乙酯更容易被中性和碱催化水解，但对酸催化水解的敏感性较低。对于来自电鳗的乙酰胆碱酯酶，催化效率[(k(cat)/ k(m))/k（中性）]为2 × 10(16) m(-1)，在量级上与作用于肽和核苷的氨基水解酶的催化效率相当。
Experiments at elevated temperatures permit the determination of rate constant and thermodynamic activation parameters for the neutral hydrolysis of the neurotransmitter acetylcholine in water. At 25 °C, the extrapolated rate constant for the uncatalyzed (or neutral) hydrolysis of acetylcholine is 3.9 × 10(-7) s(-1) at 25 °C (ΔH(‡) = 20.0 kcal/mol; TΔS(‡) = -6.1 kcal/mol). Acetylcholine is more susceptible to neutral and base-catalyzed hydrolysis than ethyl acetate but less susceptible to acid-catalyzed hydrolysis. For acetylcholinesterase from the electric eel, the catalytic proficiency [(k(cat)/K(m))/k(neutral)] is 2 × 10(16) M(-1), comparable in magnitude with the catalytic proficiencies of aminohydrolases that act on peptides and nucleosides.