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Fractionation by sucrose density gradient centrifugation of membrane fragments derived by sonic disruption of beef heart mitochondria

1973; Elsevier BV; Volume: 305; Issue: 2 Linguagem: Inglês

10.1016/0005-2728(73)90191-6

1879-2650

Cheng-Schen Huang, E. Keyhani, C.P. Lee,

Hemoglobin structure and function

1. Fractionation of beef heart submitochondrial membrane fragments derived by sonic disruption was achieved by linear sucrose density gradient centrifugation. Three distinct membrane fractions were obtained: a pellet (P), a middle (X) and an upper (Y) zone. 2. Electron micrographs revealed that the pellet contained large single pieces and aggregates of membrane fragments. The X zone contained rough membrane fragments with protruding subunits (F1) and the Y zone contained relatively small fragments without subunits. 3. In comparison with the Y zone, the X zone exhibited higher activities of NADH oxidase and ATPase, higher oligomycin-induced respiratory control and cytochrome content, but lower activities of NADH:cytochrome c reductase (rote-none-sensitive) and cytochrome oxidase with externally-added cytochrome c as the substrate. Lubrol greatly enhanced the cytochrome oxidase activity in the X zone but not in the Y zone. NADH oxidase was greatly stimulated by externally added cytochrome c in the Y zone but not in the X zone. In general, the pellet exhibited varying activities falling between those of the X zone and the Y zone. 4. The relationship between these membrane fractions and the conventional EDTA particle preparation is discussed.