Tormos_2005_J.Am.Chem.Soc_127_14538

Reference

Title : The reactant state for substrate-activated turnover of acetylthiocholine by butyrylcholinesterase is a tetrahedral intermediate - Tormos_2005_J.Am.Chem.Soc_127_14538
Author(s) : Tormos JR , Wiley KL , Seravalli J , Nachon F , Masson P , Nicolet Y , Quinn DM
Ref : Journal of the American Chemical Society , 127 :14538 , 2005
Abstract : Secondary beta-deuterium kinetic isotope effects have been measured as a function of substrate concentration for recombinant human butyrylcholinesterase-catalyzed hydrolysis of acetyl-L3-thiocholine (L = 1H or 2H). The isotope effect on V/K is inverse, D3V/K = 0.93 +/- 0.03, which is consistent with conversion of the sp2 hybridized carbonyl carbon of the scissile ester bond of the E + A reactant state to a quasi-tetrahedral structure in the acylation transition state. In contrast, the isotope effect on Vmax under conditions of substrate activation is markedly normal, D3(betaVmax) = 1.29 +/- 0.06, an observation that is consistent with accumulation of a tetrahedral intermediate as the reactant state for catalytic turnover. Generally, tetrahedral intermediates for nonenzymatic ester hydrolyses are high-energy steady-state intermediates. Apparently, butyrylcholinesterase displays an unusual ability to stabilize such intermediates. Hence, the catalytic power of cholinesterases can largely be understood in terms of their ability to stabilize tetrahedral intermediates in the multistep reaction mechanism.
ESTHER : Tormos_2005_J.Am.Chem.Soc_127_14538
PubMedSearch : Tormos_2005_J.Am.Chem.Soc_127_14538
PubMedID: 16231883

Related information

Citations formats

Tormos JR, Wiley KL, Seravalli J, Nachon F, Masson P, Nicolet Y, Quinn DM (2005)
The reactant state for substrate-activated turnover of acetylthiocholine by butyrylcholinesterase is a tetrahedral intermediate
Journal of the American Chemical Society 127 :14538

Tormos JR, Wiley KL, Seravalli J, Nachon F, Masson P, Nicolet Y, Quinn DM (2005)
Journal of the American Chemical Society 127 :14538