Mitochondria of Isolated Plant Cells (Acer pseudoplatanus L.)

The effects of copper deficiency on cell culture growth, cell respiration, mitochondrial oxidative properties, and electron transport chain have been studied with suspension-cultured sycamore cells (Acer pseudoplatanus L.). Within the range of the copper concentration studied (0.1-25 mug/1 of culture medium), the mean rate of cell division is independent of copper concentration. An initial copper concentration lower than 2 mug/1 limited the maximum density of population reached at the stationary phase of growth.On a protein basis, the uncoupled O(2) uptake rates were about the same for normal and copper-deficient cells. In contrast, the half-maximal inhibition of O(2) uptake rate was obtained at greater KCN concentration in the normal cells (20 muM) compared to copper-deficient cells (2 muM). Similar results were obtained with the normal and copper-deficient sycamore cell mitochondria.In the copper-deficient mitochondria, the concentration of the cytochrome aa(3) was less than 0.02 nmol/mg mitochondrial protein or 1/20 of the normal rate. The b- and c-type cytochrome content was invariant with copper depletion. It appeared that cytochrome aa(3) is present in large excess in normal cells. This work also indicated that cytochrome c is a very mobile molecule.