CYTOCHROMES B-558 FROM BLOOD-SERUM AND ERYTHROCYTE-MEMBRANES, ISOLATION, PURIFICATION, AND PARTIAL CHARACTERIZATION

Four types of water-soluble cytochromes b-558 were isolated and purifi ed for the first time from human placental and rat blood serum and ery throcyte membranes. They are: b-558 (I) and b-558 (II) from blood seru m and b-558 (III) and b-558 (IV) from erythrocyte membranes. The isola ted cytochromes differ in their acid-base properties, molecular weight s (110, 95, 125, and 80 kD for b-558(I-IV), respectively), composition (b-558 (III) and b-558 (IV) are lipoproteins), and absorption maxima in the wavelength range 340-360 nm. The cytochromes have nearly identi cal absorption maxima in the wavelength range 600-400 nm (560, 530, an d 412 nm in the oxidized state and 558, 525, and 420 nm in the reduced state), thus resembling cytochromes b-558 isolated from membranes of blood formed elements.