TABLE 1.

Effect of mitochondrial matrix extract on the activity of bovine mitochondrial bc₁ complex

Purified bc₁ complex was incubated with mitochondrial matrix extract (MP) or treated MP for 20 min at 4 °C before ubiquinol-cytochrome c (Cyt c) reductase activity was determined. Buffer, MP preparation buffer as control; (MP + PLA₂), MP was treated with phospholipase A₂ (PLA₂) for 30 min first; denatured MP, MP was heated at 95 °C for 30 min and then centrifuged to discard the precipitate.

Treatments	Activity	Activitya
	μmol Cyt c reduced/min/nmol Cyt b	%
bc1 + buffer	12.00 ± 0.24	100 ± 2
bc1 + MP	15.84 ± 0.24	132 ± 2
bc1 + (MP + PLA2)	15.60 ± 0.36	130 ± 3
bc1 + denatured MP	11.88 ± 0.86	99 ± 7

^a 100% activity represents 12 μmol of cytochrome c reduced/min/nmol of cytochrome b at 23 °C. n = 3, means ± S.E.