Variations in the Adenylate Levels During Phosphate Depletion in Isolated Soybean Cells and Wheat Leaf Fragments

Abstract

Summary The adenylate contents and energy charge values of isolated soybean leaf cells and wheat leaf fragments were determined after incubation with non metabolizable sugars (glucosamine or mannose) which are considered to sequestrate the intracellular inorganic phosphate. Phosphate sequestration resulted in slightly diminished energy charge values and in a decrease in total adenylate levels. No AMP accumulation was observed. The adenylate levels were maintained when the sugar was added together with an equimolecular amount of inorganic phosphate. The intracellular inorganic phosphate contents were only slightly decreased by glucosamine but a dramatic inhibition of the photosynthetic CO 2 fixation activity was observed. The results suggest a regulation of the intracellular adenylate levels by inorganic phosphate the function of which would be to prevent large variations in energy charge and sharp increases in AMP levels.