The Evolution of Enzymatic Activity in the Crotonase Superfamily: The Mechanism of the Reaction Catalyzed by 2-Ketocyclohexanecarboxyl-Coa Hydrolase

Abstract

The stereochemical progress of the reaction catalyzed by BadI is important for understanding the catalytic roles of residues in the active site. It was concluded that, unlike other stereochemically characterized crotonase homologs, this reaction must proceed via a Z-enolate. Based on the information derived from stereochemical studies and site-specific mutagenesis, a mechanism of the reaction catalyzed by BadI was proposed, in which Ser 138 plays a central catalytic role. The new data is also related to the homologous 1,4-dihydroxy-2-naphthoyl-CoA synthase (MenB), which has the same active-site configuration as that of BadI but catalyzes a forward Dieckmann reaction in microbial menaquinone biosynthesis.