"Apocatalase" of Catalase-Negative Staphylococci.

Crystalline catalase of high purity and activity was prepared from a heme-requiring Staphylococcus aureus mutant, JT/52, grown in the presence of heme. A crystalline protein was obtained from the same cells grown without heme. This enzymatically inactive protein and the catalase cross-react strongly when tested by a variety of immunochemical tests.