Quantitative Analysis of Phytate Globoids Isolated from Wheat Bran and Characterization of Their Sequential Dephosphorylation by Wheat Phytase

Abstract

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 K(m) 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.

Dynamic Changes in the Distribution of Minerals in Relation to Phytic Acid Accumulation during Rice Seed Development

“…However, in these studies, Cu and Zn may have had a high affinity for InsP 6 . In contrast to these in vitro results, in vivo InsP 6 is stored mainly with Mg and K in rice and corn (Zea mays) seeds (Ogawa et al, 1975;Lin et al, 2005) and with Mg, K, and Ca in wheat (Triticum aestivum) seeds (Bohn et al, 2007). In this study, m-XRF analysis at a 1-mm step size also indicated that Ca, K, and Fe bind strongly to phytic acid, Zn binds loosely, and Cu scarcely binds to phytic acid.…”

Phytic acid degrading lactic acid bacteria in tef-injera fermentation

“…As the matrix surrounding the substrate has a strong impact on the extent of PA degradation by phytases (Bohn et al, 2007;Brejnholt et al, 2011) model fermentations with tef flour were used to test the PA degradation potential of the different LAB species isolated from the Ethiopian fermented tef-injera batter. The highest PA degradation in the model fermentations with selected LAB was seen after incubation with the L. buchneri and P. pentosaceus strains which showed roughly three times higher degradation than observed in the antibiotic treated approach, reducing the PA to less than half of the level in native tef.…”

A decrease in phytic acid content substantially affects the distribution of mineral elements within rice seeds

“…InsP 6 serves as a phosphorus (P) storage substance in plants. In plant seeds, about 75 ± 10% of total P is accumulated as InsP 6 [1], and InsP 6 is deposited primarily as mixed salts of various mineral cations such as magnesium (Mg), potassium (K), calcium (Ca), manganese (Mn), iron (Fe), and zinc (Zn) [2,3] because InsP 6 has six negatively charged phosphate groups and can chelate strongly with the cations to form insoluble salts; i.e., phytate.…”