FIG. 2.

Copper depletion leads to reduced activity of COX and to the induction of the alternative oxidase. (A) Photometric determination of COX activity in the wild-type strain and mutant grisea. Three micrograms of mitochondrial protein was incubated with reduced cytochrome c as described in Materials and Methods. The protein preparation and measurements were repeated three times. (B) Oxygen uptake measurements of the wild-type strain, mutant grisea, and mutant ex1, without addition of respiratory inhibitors, with addition of 1 mM KCN, or with addition of 4 mM SHAM. (C) Oxygen uptake measurements of the wild-type strain grown on 30 μM BCS and 1 mM ascorbic acid and of mutant grisea grown on 100 μM CuSO₄. Experiments described for panels B and C were carried out at least in triplicate with two or three independent isolates of each strain.