METALLOPROTEIN NATURE OF USTILAGO DELTA-AMINOLEVULINATE DEHYDRATASE

1. 1. The δ-aminolevulinate dehydratase of Ustilago sphaerogena has been purified approx. 40-fold. 2. 2. The enzyme was strongly inhibited by a number of nonspecific metal-binding agents, such as 1,10-phenanthroline. The inhibitory power of the ligands was greatly augmented by preincubation with the enzyme. 3. 3. Agents specific for Cu+ were powerful inhibitors, while those specific for Cu2+ were without effect. 4. 4. Attempts to reconstitute the ligand-treated enzyme by incubation with various copper compounds were frustrated by the extreme susceptibility of the enzyme to inhibition by copper. 5. 5. Partial reactivation of the ligand-treated enzyme could be achieved with Zn2+. 6. 6. A moderately good correlation was found between enzyme activity and the copper content of the purified enzyme. © 1969.