Heme A of Cytochrome c Oxidase

A new procedure for the isolation of the green a-type heme from bovine heart muscle is described. The heme is extracted with a pyridine-chloroform mixture and separated from lipids and other hemes chromatographically. The product is obtained in nearly quantitative yield, either as a pyridine iron(II) complex or as a disodium salt of a hydroxo iron(III) complex. No evidence was found to suggest that the cytochrome a and a3 components of cytochrome c oxidase have hemes of different structure, nor was a cryptohemin component detected. A previously undetected group of approximate composition C6H12NO4 was isolated as a part of the green heme, and for this reason the hemes isolated by the procedure described here have been designated heme A derivatives to distinguish them from heme a or cytohemin derivatives obtained by other workers with the Warburg and Gewitz procedure.