Purification and some properties of wheat germ acid phosphatases

Acid phosphatase isozymes were isolated from wheat germ. Six isozymes were isolated, and one of them was purified to homogeneity. The molecular mass of the purified isozyme was revealed to be 40 kDa (from an SDS-PAGE analysis), or 47 kDa (from a gel filtration analysis), suggesting that the isozyme is a monomer. The N-terminal amino acid sequence of the isozyme was also determined. All of the isozymes showed similar properties; optimum pH, substrate specificities and metal ion inhibition. However, three isozymes were able to hydrolyze phosphotyrosine, but the others were not. Mouse antiserum raised against the purified isozyme could react with other partially purified isozymes except for one isozyme, suggesting that at least five isozymes isolated in this study immunochemically have common epitopes.