Purification and properties of D-4-deoxy-5-oxoglucarate hydro-lyase (decarboxylating).

1. An enzyme extracted from Pseudomonas acidovorans was purified and shown to catalyse the simultaneous dehydration and decarboxylation of d-4-deoxy-5-oxoglucarate. It is proposed to name the enzyme d-4-deoxy-5-oxoglucarate hydro-lyase (decarboxylating), trivial name ;deoxyoxoglucarate dehydratase'. 2. No added cofactors were required, and the enzyme was inactivated when incubated with its substrate in the presence of sodium borohydride. Under these conditions the substrate and enzyme appeared to be bound covalently. 3. The action of the enzyme is readily explained if it is assumed that d-4-deoxy-5-oxoglucarate forms a Schiff base with a lysine residue in the enzyme.