Bovine cardiolipin

Detergent solubilized lipid micelles were prepared as described before (4 (link)). Briefly, a desired amount of E. coli polar lipid extract (EPL), 0.67 POPE/0.33 POPG (2:1 POPE/POPG), or 0.67 POPE/0.23 POPG/0.1 bovine cardiolipin (Avanti Polar Lipids Inc.) in chloroform (25 mg/mL stock) was dispensed in a glass vial. The chloroform was evaporated under a continuous stream of 0.22-μm filtered Ultra High Purity N₂ gas (Airgas), and then the lipids were washed in pentane and then dried while rotating the vial, for approximately 10 to 12 min, leaving a thin film of lipids along the walls and the bottom of the tube. After repeating the washing step twice, the lipid film was resuspended in Dialysis Buffer (DB: 300 mM KCl, 20 mM citrate pH 4.5, adjusted with NaOH) to a final concentration of 20 mg/mL, and 35 mM of 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS) was added. The lipid/detergent mixture was solubilized using a cup-horn sonicator (Qsonica) until the sample achieved a homogenous translucent appearance.