Paper
Reaction of cis-3-chloroacrylic acid dehalogenase with an allene substrate, 2,3-butadienoate: hydration via an enamine.
Published Jan 11, 2012 · G. Schroeder, W. Johnson, Jamison P. Huddleston
Journal of the American Chemical Society
19
Citations
0
Influential Citations
Abstract
cis-3-Chloroacrylic acid dehalogenase (cis-CaaD) catalyzes the hydrolytic dehalogenation of cis-3-haloacrylates to yield malonate semialdehyde. The enzyme processes other substrates including an allene (2,3-butadienoate) to produce acetoacetate. In the course of a stereochemical analysis of the cis-CaaD-catalyzed reaction using this allene, the enzyme was unexpectedly inactivated in the presence of NaBH(4) by the reduction of a covalent enzyme-substrate bond. Covalent modification was surprising because the accumulated evidence for cis-CaaD dehalogenation favored a mechanism involving direct substrate hydration mediated by Pro-1. However, the results of subsequent mechanistic, pre-steady state and full progress kinetic experiments are consistent with a mechanism in which an enamine forms between Pro-1 and the allene. Hydrolysis of the enamine or an imine tautomer produces acetoacetate. Reduction of the imine species is likely responsible for the observed enzyme inactivation. This is the first reported observation of a tautomerase superfamily member functioning by covalent catalysis. The results may suggest that some fraction of the cis-CaaD-catalyzed dehalogenation of cis-3-haloacrylates also proceeds by covalent catalysis.
Cis-3-chloroacrylic acid dehalogenase can produce acetoacetate by covalent catalysis with an allene substrate, suggesting some fraction of its dehalogenation may also occur by this mechanism.
Sign up to use Study Snapshot
Consensus is limited without an account. Create an account or sign in to get more searches and use the Study Snapshot.
Full text analysis coming soon...