Fractionation and Purification of Cytochrome C Photooxidase of Spinach.

Abstract

A procedure is described for fractionating cytochrome c photooxidase into 2 heat-labile components, 1 of which contains chlorophyll bound in a lipoprotein complex containing both phospholipid and nucleic acid. This component, called Factor 1, is insoluble in water, except in the presence of digitonin. The other component, called Factor 2, is water soluble and can be purified by fractional precipitation with acetone and ammonium sulfate. The best preparations of Factor 2 are about 1000 times more active on a protein basis than the whole leaf. The photo-oxidation of cytochrome c is shown to be dependent on the simultaneous presence of both of these components.