Protein Extraction, Acid Phosphatase Activity Assays, and Determination of Soluble Protein Concentration

Abstract

Acid phosphatases (APases) catalyze the hydrolysis of inorganic phosphate (Pi) from a broad range of Pi-monoesters with an acidic pH optimum. The liberated Pi is reassimilated into cellular metabolism via mitochondrial or chloroplastic ATP synthases of respiration or photosynthesis, respectively. Eukaryotic APases exist as a wide variety of tissue- and/or cellular compartment-specific isozymes that display marked differences in their physical and kinetic properties. Increases in intracellular (vacuolar) and secreted APase activities are useful biochemical markers of plant nutritional Pi deficiency. The protocols for protein extraction, APase activity determination and measurement of soluble protein concentration from plant tissues or cell suspension cultures are presented.