G. Capitani, M. Tschopp, A. C. Eliot
Apr 25, 2005
Citations
0
Influential Citations
23
Citations
Journal
FEBS Letters
Abstract
l‐Vinylglycine (l‐VG) is both a substrate for and a mechanism‐based inhibitor of 1‐aminocyclopropane‐1‐carboxylate (ACC) synthase. The ratio of the rate constants for catalytic conversion to α‐ketobutyrate and ammonia to inactivation is 500/1. The crystal structure of the covalent adduct of the inactivated enzyme was determined at 2.25 Å resolution. The active site contains an external aldimine of the adduct of l‐VG with the pyridoxal 5′‐phosphate cofactor. The side chain γ‐carbon of l‐VG is covalently bound to the ε‐amino group of Lys273. This species corresponds to one of the two alternatives proposed by Feng and Kirsch [Feng, L. and Kirsch, J.F. (2000) l‐Vinylglycine is an alternative substrate as well as a mechanism‐based inhibitor of 1‐aminocyclopropane‐1‐carboxylate synthase. Biochemistry 39, 2436–2444] and presumably results from Michael addition to a vinylglycine ketimine intermediate.