Fig. 2.
Energetic origins of β-secondary deuterium isotope effects for the formation of the tetrahedral intermediate in the acylation stage of BuChE-catalyzed hydrolysis of ATCh. Verticle arrows denote values of ΔEa, and are labeled with the corresponding isotopic reaction rate or equilibrium constant. Interpretation of isotope effects in terms of structural changes in the substrate is discussed in the text.