Purification and characterization of a phytate-degrading enzyme from germinated oat (Avena sativa)

A phytate-degrading enzyme (myo-inositol hexakisphosphate phosphohydrolase) has been purified about 5,400-fold from germinated oat seedlings to appare nt homogeneity. The molecular mass of the native monomeric enzyme was estim ated to be about 67 kDa. Optimal pH for degradation of phytate was 5.0 and the optimal temperature 38 degrees C. Kinetic parameters for the hydrolysis of Na-phytate are K-M 30 mu M and k(cat) 356 s(-1) at 35 degrees C and pH 5.0. The oat phytase exhibits a broad affinity for various phosphorylated c ompounds and hydrolyses phytate in a stepwise manner. The first hydrolysis product was identified as D/L-1(1,2,3,4,5) P-5. (C) 1999 Society of Chemica l Industry.