Purification and characterization of a phytate-degrading enzyme from germinated faba beans (Vicia faba var. Alameda)

A phytate-degrading enzyme was purified similar to 2190-fold from germinated 4-day-old faba bean seedlings to apparent homogeneity with a recovery of 6% referred to the phytase activity in the crude extract. It behaves as a monomeric protein of a molecular mass of similar to 65 kDa. The phytate-degrading enzyme belongs to the acidic phytases. It exhibits a single pH optimum at 5.0. Optimal temperature for the degradation of sodium phytate is 50 degreesC. Kinetic parameters, for the hydrolysis of sodium phytate are K-M = 148 mu mol L-1 and k(cat) = 704 s(-1) at 35 degreesC and pH 5.0. The faba bean phytase exhibits a broad affinity for various phosphorylated compounds and hydrolyzes phytate in a stepwise manner. The first hydrolysis product was identified as D/L-myo-inositol(1,2,3,4,5)pentakisphosphate.