Purification and properties of an erythrocyte hemoprotein with a unique prosthetic group.

I. A unique hemoprotein has been isolated from a hemolysate of normal human erythrocytes by a procedure which involves (NH4),SO 4 precipitation and chromatography on Amberlite CG-5o, DEAE-cellulose, Bio-Gel P-6o, and Bio-Gel P-3o. 2. The purified hemoprotein appeared homogeneous on ultracentrifugation although small amounts of impurities were detected by polyacrylamide gel electrophoresis. The molecular weight was estimated to be 21 ooo by gel filtration. Absorption maxima were located at 416 m/~ for the oxidized form, 430 m# for the CNcomplex of the oxidized form, 434 m# for the reduced form, and 425 m# for the CO derivative of the reduced form. The reduced pyridine hemochrome of the isolated prosthetic group has maxima at 434, 54 o, and 579 m#, clearly indicating that the protein possesses a previously unrecognized heme.