2-Haloacrylate hydratase from Pseudomonas sp. YL catalyzes the hydration of 2-chloroacrylate to produce pyruvate and HCl. Although the conversion does not involve a net change in the redox state, the enzyme requires reduced FAD, which is not consumed during substrate turnover. It was not clear how the reduced form of FAD is generated in vivo. The examination of the primary structure of the enzyme has revealed the presence of an unusual nucleotide-binding fingerprint motif consisting of the sequence AXXGXXG; this finding suggests that the enzyme may bind to NADH or NADPH. The UV-visible spectroscopic analyses indicated that 2-haloacrylate hydratase catalyzes the reduction of FAD at the expense of NADH. Thus, 2-haloacrylate hydratase is a bifunctional enzyme with both NADH-dependent FAD reductase activity and FADH2-dependent 2-haloacrylate hydratase activity.

Abbreviations: 2-CAA, 2-chloroacrylic acid, DTT, dithiothreitol