Purification and properties of a phytate-degrading enzyme from Pantoea agglomerans.
A periplasmatic phytate-degrading enzyme from Pantoea agglomerans isolated from soil was purified about 470-fold to apparent homogeneity with a recovery of 16% referred to the phytate-degrading activity in the crude extract. It behaved as a monomeric protein with a molecular mass of about 42 kDa. The purified enzyme exhibited a single pH optimum at 4.5. Optimum temperature for the degradation of phytate was 60 degrees C. The kinetic parameters for the hydrolysis of sodium phytate were determined to be KM = 0.34 mmol/l and kcat = 21 s(-1) at pH 4.5 and 37 degrees C. The enzyme exhibited a narrow substrate selectivity. Only phytate and glucose-1-phosphate were identified as good substrates. Since this Pantoea enzyme has a strong preference for glucose-1-phosphate over phytate, under physiological conditions glucose-1-phosphate is its most likely substrate. The maximum amount of phosphate released from phytate by the purified enzyme suggests myo-inositol pentakisphosphate as the final product of enzymatic phytate degradation.
Greiner
Ralf
R
Centre for Molecular Biology, Federal Research Centre for Nutrition and Food, Haid-und-Neu-Strasse 9, D-76131 Karlsruhe, Germany. ralf.greiner@bfe.uni-karlsruhe.de
D010832:6-Phytase / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000378:metabolism; D002413:Cations, Divalent / Q000494:pharmacology; D004790:Enzyme Induction; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D012275:Oryza / Q000382:microbiology; D020636:Pantoea / Q000201:enzymology*; D013379:Substrate Specificity
D002413:Cations, Divalent; D010832:6-Phytase