Acid phosphatase from mung bean (Vigna radiata) germinated seeds was partially purified via ammonium sulfate precipitation and fully purified via gel excision and heat denaturation, yielding a 29 kDa protein. Using 4-nitrophenylphosphate as a substrate, Vmax and Km values of 0.10 µmol/min and 0.27 mM, respectively, were obtained. The acid phosphatase was heat resistant, enhanced by the presence of Fe2+ and Mn2+ salts, and inhibited by the presence of citrate. Mung bean acid phosphatase reacted immunologically with primary antibodies against Solanum tuberosum acid phosphatase, while polymerase chain reaction (PCR) analyses suggest there are some common sequences between mung bean acid phosphatase DNA and that of Arabidopsis thaliana acid phosphatase vegetative storage protein. This suggests plant acid phosphatases are structurally as well as functionally related.
Key words: Acid phosphatase, mung bean, Vigna radiata, vegetative storage protein.