Summary

Trans-3-chloroacrylic dehalogenase, an enzyme that resembles 4-oxalocrotonate tautomerase in shape and function, catalyzes the conversion of trans-3-chloroacrylic acid to malonate semialdhyde. The non-catalyzed half-life of 24,000 years demonstrates the importance of CaaD in catalyzing this reaction, since its precursor, 1,3-dichloropropene, is a potentially toxic pesticide still used to kill crop-eating nematodes all over the world. This work is important in our understanding of the enzyme kinetics of other hydrating enzymes, such as fumarate and 4-OT, because changes in the structure and amino acids present in the active site equate to the enhancement of this reaction over other, similar hydration/elimination reaction. Only by understanding what changes in an enzyme lead to such significant rate enhancements of a non-catalyzed reaction can we truly understand the nature of the structure function relationship, which forms the crux of much modern protein biochemistry.