Purification, characterization and comparison of two non-haem bromoperoxidases from Streptomyces aureofaciens ATCC 10762

Summary: Two non-haem bromoperoxidases (BPO 1 and BPO 2) were purified from the 7-chlorotetracycline-producing strain Streptomyces aureofaciens ATCC 10762. Both enzymes showed azide-insensitive brominating activity, and bromide-dependent peroxidase activity. BPO 1 was a dimer (M r 65000) with subunits of identical size (M r 31000). The pI was estimated to be 4·5. The enzyme did not cross-react with antibodies raised against the non-haem bromoperoxidase (M r 90000) from S. aureofaciens Tu24, a strain that also produces 7-chlorotetracycline. The M r of BPO 2 was estimated to be 90000. The enzyme had three identical subunits (M r 31000), and its isoelectric point was 3·5, identical with that of the bromoperoxidase from S. aureofaciens Tu24. Moreover, BPO 2 was immunologically identical with the bromoperoxidase from S. aureofaciens Tu24, although both it and BPO 1 could be distinguished electrophoretically from the latter bromoperoxidase.