Purification of cytochrome b from complex III of beef heart mitochondria.
Two cytochrome b preparations have been prepared from Complex III of beef heart mitochondria, by detergent-exchange chromatography on a butyl-Toyopearl column. One was eluted from the column with buffer containing Tween 20 after most of other subunits of Complex III were eluted with buffer containing guanidine-HCl, and the other was eluted from the column with buffer containing sodium dodecyl sulfate. The former is consisted of a single polypeptide (subunit III) and contained 37.5 nmol of heme b/mg of protein, and the latter consisted of subunits III and IX and contained 19.5 nmol of heme b/mg of protein. The former was labile when it was reduced by dithionite, whereas the latter was stable. Subunit IX in the latter is associated with cytochrome b even after gel filtration and density gradient centrifugation. These results suggest that subunit IX plays a role in stabilizing cytochrome b.
D000818:Animals; D002417:Cattle; D003573:Cytochrome b Group / Q000032:analysis / Q000302:isolation & purification*; D014450:Electron Transport Complex III; D004591:Electrophoresis, Polyacrylamide Gel; D006418:Heme / Q000032:analysis; D008929:Mitochondria, Heart / Q000201:enzymology*; D008970:Molecular Weight; D009097:Multienzyme Complexes / Q000032:analysis*; D011808:Quinone Reductases / Q000032:analysis*; D013053:Spectrophotometry
D003573:Cytochrome b Group; D009097:Multienzyme Complexes; D006418:Heme; D011808:Quinone Reductases; D014450:Electron Transport Complex III