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. Author manuscript; available in PMC: 2008 Nov 2.
Published in final edited form as: J Am Chem Soc. 2007 Apr 5;129(17):5378–5380. doi: 10.1021/ja0712064

Figure 1.

Figure 1

Possible acylation mechanisms of class A β-lactamases. (a) The overall reaction pathway for β-lactam hydrolysis. Beginning with a ground-state Michaelis complex (i), catalysis proceeds through a high-energy acylation transition state (ii) to an acyl-enzyme intermediate (iii). These steps constitute the acylation half of the reaction. Deacylation then proceeds through a high-energy deacylation transition state (iv) and a postcovalent product complex (v), after which the product leaves. (b) Acylation mechanism 1: a neutral Lys73 as the general base. Hydrogen bonds are indicated by blue dashed lines and electron transfer by purple arrows. (c) Acylation mechanism 2: Glu166 as the general base, through the catalytic water (wat1). Lys73 is positively charged in this model.