72a] Isolation of a mitochondrial membrane fraction containing the citric acid cycle and ancillary enzymes

Abstract

In the preparation of submitochondrial particles from beef heart mitochondria, the interest has been centered on the isolation and purification of particles concerned with the electron transfer process. The classical preparation of the electron transfer particles (ETP) is composed of membranous vesicles comprised of the characteristic tripartite repeating units. This membrane fraction is more concentrated than the mitochondrion in respect to the oxidation-reduction components of the electron transfer chain, but significantly less concentrated in respect to the enzymes of the citric acid cycle. Another membrane fraction also can be isolated, which contains the citric acid cycle enzymes and no electron transfer components. The fractionation procedure can be monitored by observing the decrease in electron transfer components or the increase in the enzymes of the citric acid cycle. This chapter examines the isolation of a mitochondrial membrane fraction containing the citric acid cycle and ancillary enzymes, and discusses the fractionation and distribution of enzymic activities between the two mitochondrial membranes.