Electron Transport Systems of Yeast

Abstract

Abstract Cytochrome oxidase, prepared from the electron transport particles of yeast, has been purified approximately 5- to 6-fold. The enzyme preparation contained copper, nonheme iron, labile sulfide, and cytochromes a + a3 in approximately equimolar amounts, and 25 to 30% lipid on a dry weight basis. Difference spectra (reduced minus oxidized) of the enzyme preparation showed absorption maxima at 445 and 604 mµ and a small broad peak at 650 to 750 mµ, but no change in absorbance was found in the region 800 to 900 mµ. Yeast cytochrome oxidase was strongly inhibited by cyanide, azide, diethyldithiocarbamate, and ethylenediaminetetraacetate, but not by p-chloromercuriphenyl sulfonic acid or antimycin A.