Catalase

Sumner and Dounce¹ have recently observed that on splitting with acids crystalline ox liver catalase yields a `blue substance', which remains in the aqueous acetone mother liquor after the hæmin crystals have come out. This mother liquor contained approximately the same amount of iron as the hæmin crystals. The authors concluded from these observations that catalase has two bile pigment hæmatin groups in addition to two protohæmatin groups in a molecule of the weight 248,000, and that the blue substance, though not identical with the original prosthetic group in catalase, still contains iron and differs from biliverdin.