Bohn, Lisbeth5; Josefsen, Lone2; Meyer, Anne S.4; Rasmussent, S.K.5
1 Department of Systems Biology, Technical University of Denmark2 Risø National Laboratory for Sustainable Energy, Technical University of Denmark3 Center for BioProcess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark4 Department of Chemical and Biochemical Engineering, Technical University of Denmark5 unknown
Wheat phytase was purified to investigate the action of the enzyme toward its pure substrate (phytic acid - myo-inositol hexakisphosphate) and its naturally occurring substrate (phytate globoids). Phytate globoids were purified to homogeneity from wheat bran, and their nutritionally relevant parameters were quantified by ICP-MS. The main components of the globoids were phytic acid (40% w/w), protein (46% w/w), and several minerals, in particular, K > Mg > Ca > Fe (in concentration order). Investigation of enzyme kinetics revealed that Km and V-max decreased by 29 and 37%, respectively, when pure phytic acid was replaced with phytate globoids as substrate. Time course degradation of phytic acid or phytate globoids using purified wheat phytase was followed by HPIC identification of inositol phosphates appearing and disappearing as products. In both cases, enzymatic degradation initiated at both the 3- and 6-positions of phytic acid and end products were inositol and phosphate.
Journal of Agricultural and Food Chemistry, 2007, Vol 55, Issue 18, p. 7547-7552