Respiratory and ATP hydrolysis/synthesis activities of mitochondria.

Mitochondria were isolated from yeast cells grown at 28°C in rich glycerol+ethanol (YPEG) or rich galactose (YPGALA), as indicated. All cultures contained less than 5% ρ−/ρ0 cells, except that of Δatp9 where about 50% ρ−/ρ0 cells were scored. Additions were 0.15 mg/ml proteins, 4 mM NADH, 150 mM ADP, 4 mM CCCP, and 3 µg/ml oligomycin (Oligo). The values reported are averages of triplicate assays ± standard deviation. Respiratory and ATP synthesis activities were measured on freshly isolated, osmotically-protected mitochondria buffered at pH 6.8. For the ATPase assays, mitochondria kept at −80°C were thawed and the reaction was performed in absence of osmotic protection at pH 8.4. ND, not determined.