Figure 1.
AOX activity in leaf mitochondria isolated in the presence of different concentrations of pyruvate. Transgenic tobacco (B9) mitochondria were isolated with pyruvate (0–5 mm) present in all of the isolation media and analyzed for AOX activity in an assay medium using an O2 electrode, as described in “Materials and Methods.” A, Effect of pyruvate concentration in the mitochondrial isolation medium on subsequent AOX activity in the presence of saturating (2 mm) pyruvate in the assay medium (+pyr, ♦) and after subsequent addition of 10 mm DTT to the assay medium (+pyr +DTT, ●). Each set of points (one +pyr, one +pyr +DTT) represents data from a separate mitochondrial isolation. B, Effect of pyruvate concentration in the mitochondrial isolation medium on DTT-independent AOX activity. Activity (in the presence of 2 mm pyruvate in the assay medium) is expressed as a percentage of activity with 2 mm pyruvate and 10 mm DTT in the assay medium. Data are derived from those in A.