Light-mediated activation of stromal sedoheptulose bisphosphatase.

When isolated wheat (Triticum aestivum) chloroplasts were illuminated, the activity of sedoheptulose bisphosphatase increased severalfold. The rate of activation was limited by the size of the carbon pool, and experiments with a partially purified enzyme preparation showed that the degree of reductive activation of the enzyme is governed by the concentration of its substrate.