Intracellular Distribution of p-Nitrophenyl-Phosphatase in Plants

Less than 10% of the acid p-nitrophenylphosphatase activity of plant extracts was sedimentable under a variety of conditions including zonal centrifugation. The sedimentable fraction did not show the latency properties characteristic of animal lysosomes. We conclude that, at least operationally, plant acid phosphatase is a soluble enzyme and that it is not suitable as a lysosomal marker. The plant tissues employed were pea cotyledons, cauliflower florets, turnip storage organs, onion embryos, and leaves of red oak and soybean.