The isolation and properties of microsomal cytochrome.

Mammalian liver contains a heme protein which from its spectrum and properties in particulate preparations has been termed cytochrome b, by Yoshikawa (I), cytochrome m by C. F. Strittmatter and Ball, who localized it in microsomes (2,3), and cytochrome bg by Chance and Williams (4). In view of the fact that this and other microsomal enzymes have been studied chiefly in particulate suspensions, methods of isolating microsomal proteins for more detailed characterization were examined. The first and most easily recognizable of the enzymes that we have obtained is the microsomal cytochrome. This paper deals with the liberation of the cytochrome from its particulate complex, the fractionation steps in its purification, electrophoretic and ultracentrifugal tests for homogeneity, molecular weight determination, spectral properties, and reactions with a number of reagents.