Stereospecificity of myo-inositol hexakisphosphate dephosphorylation by a phytate-degrading enzyme of baker's yeast.
During food processing such as baking, phytate is dephosphorylated to produce degradation products, such as myo-inositol pentakis-, tetrakis-, tris-, bis-, and monophosphates. Certain myo-inositol phosphates have been proposed to have positive effects on human health. The position of the phosphate groups on the myo-inositol ring is thereby of great significance for their physiological functions. Using a combination of high-performance ion chromatography analysis and kinetic studies the stereospecificity of myo-inositol hexakisphosphate dephosphorylation by a phytate-degrading enzyme from baker's yeast (Saccharomyces cerevisiae) was established. The data demonstrate that the phytate-degrading enzyme from baker's yeast dephosphorylates myo-inositol hexakisphosphate in a stereospecific way by sequential removal of phosphate groups via D-Ins(1,2,4,5,6)P(5), D-Ins(1,2,5,6)P(4), D-Ins(1,2,6)P(3), D-Ins(1,2)P(2), to finally Ins(2)P (notation 3/4/5/6/1). Knowledge of the absolute stereochemical specificity of the baker's yeast phytase allows use of the enzyme to produce defined myo-inositol phosphates for kinetic and physiological studies.
Greiner
R
R
Centre for Molecular Biology, Federal Research Centre for Nutrition, Haid-und-Neu-Strasse 9, D-76131 Karlsruhe, Germany, and Department of Food Science, Chalmers University of Technology, c/o SIK, Box 5401, SE-402 29 Göteborg, Sweden.
Alminger
M L
ML
Carlsson
N G
NG
D010832:6-Phytase / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D007295:Inositol Phosphates / Q000737:chemistry* / Q000378:metabolism*; D007536:Isomerism; D007700:Kinetics; D010766:Phosphorylation; D012441:Saccharomyces cerevisiae / Q000201:enzymology*
D007295:Inositol Phosphates; D010832:6-Phytase