Crystallization of mitochondrial ubiquinol-cytochrome c reductase.
Ubiquinol-cytochrome c reductase of beef heart mitochondria was crystallized in the presence of decanoyl-N-methylglucamide, heptanetriol, and sodium chloride with poly(ethylene glycol) as precipitant. The largest crystal has dimensions of 4 x 2 x 1 mm. The crystalline enzyme is composed of 10 subunits. It contains 2.5 nmol of ubiquinone, 8.4 nmol of cytochrome b, 4.2 nmol of cytochrome c1, 4.2 nmol of iron-sulfur cluster, and 140 nmol of phospholipid per milligram of protein. Of the last, 36% is with diphosphatidylglycerol. The crystals are very stable in the cold and show full enzymatic activity when redissolved in aqueous solution. Absorption spectra of the redissolved crystals show a Soret to UV ratio of 0.88 and 1.01 in the oxidized and the reduced forms, respectively.
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Department of Biochemistry, Oklahoma State University, Stillwater 74078.
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D000818:Animals; D002417:Cattle; D003460:Crystallization; D014450:Electron Transport Complex III / Q000737:chemistry* / Q000302:isolation & purification; D004591:Electrophoresis, Polyacrylamide Gel; D008929:Mitochondria, Heart / Q000201:enzymology*; D008970:Molecular Weight; D010743:Phospholipids / Q000032:analysis; D013053:Spectrophotometry
D010743:Phospholipids; D014450:Electron Transport Complex III