Stereospecificity of My0-Inositol Hexakisphosphate Dephosphorylation by Phytate-Degrading Enzymes of Cereals

Using a combination of High-Performance Ion Chromatography analysis and kinetic studies the stereospedfidty of myo-inositol hexakisphosphate dephosphorylation by the spelt phytase D21, the rye phytase, the barley phytases P1 and P2, and the oat phytase was established. The data demonstrate that all the cereal phytate-degrading enzymes under investigation dephosphorylate myo-inositol hexakisphosphate in a stereospecific way by sequential removal of phosphate groups via D-Ins(l,2, 3,5, 6)P5, D-Ins(l,2, 5,6)P4, D-Ins(l,2, 6)P3, D-Ins(l,2)P2 to finally Ins(2)P (notation 4/3/5/6/1).