Purification and Inhibition of Spinach &α,&β-Dihydroxyacid Dehydratase

Article abstract of DOI:10.1021/jo00268a014

The α,β-dihydroxyacid dehydratase (E.C. 4.2.1.9) responsible for the production of α-oxoisovaleric acid in the valine biosynthetic pathway has been purified from spinach leaves.Its properities are similar to those given in a previous report using a less pure preparation.Its monomer mass is estimated to be 55 kDa.Evidence for an enol intermediate in the reaction mechanism has been obtained by a deuterium labeling study.Several inhibitors have been screened against the enzyme.Four of particular effectiveness are 4-fluoro-3,3-dihydroxyisovaleric acid, 1-hydroxy-1-isobutanesulfonic acid, N,N-dimethylglycine N-oxide, and 2-fluoro-3,3-dimethylacrylic acid.As an enol analogue, the latter compound gives further evidence for enol itermediate.