Purification and properties of a phytase from rye

Phytase (myo-inositol hexakisphosphate phosphohydrolase) has been purified about 2,000-fold from ungerminated rye with a recovery of 6%. The enzyme behaves as a monomeric protein of a molecular mass of about 67 kDa. Optimal pH for the degradation of phytate has been found at pH 6.0 and 45C. Kinetic parameters for the hydrolysis of Na-phytate are K(M) 300 mu M and k(cat) 358 s(-1) at 35C and pH 6.0. The rye enzyme exhibits a broad affinity for various phosphorylated compounds and hydrolyses phytate in a stepwise manner; the pentakis- and tetrakisphosphate were identified as 1(1, 2, 3, 4, 5)P(5) and 1(2, 3, 4, 5)P(4). Consequently, this enzyme is a 6-phytase (EC 3.1.3.26).