Distribution of Pyrophosphate:Fructose 6-Phosphate Phosphotransferase in Maize Leaves

Abstract

In leaves of maize (Zea mays) the activity of pyrophosphate:fructose 6-phosphate 1-phosphotransferase (PFP) is much less than that of ATP:fructose 6-phosphate 1-phosphotransferase. A sequential extraction technique was used to study the location of PFP in this tissue. When compared with enzymes known to be restricted to specific locations in maize, the distribution of PFP activity in the sequential extracts indicated that PFP is located predominantly, if not exclusively, in the mesophyll cytoplasm. Although confined to the same site as sucrose synthesis, the level of PFP activity is inadequate to contribute significantly to the gluconeogenic flux from fructose 1,6-bisphosphate to fructose 6-phosphate. The absence of PFP activity from the bundle-sheath demonstrates that this activity is not essential for glycolysis in higher plants.