Purification and some properties of the main polymorphic form of acid phosphatase from Poa pratensis seeds.

The main polymorphic form of acid phosphatase was isolated from Poa pratensis seeds by chromatography on DEAE- and CM-cellulose and gel filtration on Bio-Gel P-100. The enzyme migrated as a single band in disc electrophoresis at pH 4.5 and 8.4. The purified enzyme is a glycoprotein of molecular weight about 33 000. Carbohydrate content accounts for 40% of the total weight. The optimum pH is at 5.2 and the apparent Km for p-nitrophenylphosphate, 0.55 mM. Fluoride ions are non-competitive and zinc ions-uncompetitive inhibitors, with the apparent Km values of 0.55 and 0.28 mM, respectively.