TY - JOUR
T1 - Mechanisms and pathways of phytate degradation
T2 - Evidence from oxygen isotope ratios of phosphate, HPLC, and phosphorus-31 NMR spectroscopy
AU - Wu, Jiangqi
AU - Paudel, Prajwal
AU - Sun, Mingjing
AU - Joshi, Sunendra R.
AU - Stout, Lisa M.
AU - Greiner, Ralf
AU - Jaisi, Deb P.
N1 - Publisher Copyright:
© Soil Science Society of America, 5585 Guilford Rd., Madison WI 53711 USA. All Rights reserved.
PY - 2015/11/1
Y1 - 2015/11/1
N2 - Phytate, the salt of myo-inositol hexakisphosphate, and its partially dephos-phorylated products are commonly present in the environment, but their origins and bioavailability are not well understood. This research applied phosphate O isotope ratios (δ18Op) in combination with nuclear magnetic resonance (NMR) and high-performance liquid chromatography (HPLC) methods to characterize the kinetics and pathways of phytate degradation by wheat phytase and the O isotopic composition during progressive degradation of phytate. Our results show that phytate degradation undertakes two pathways: D-inositol-1,2,3,5,6-pentakisphosphate, D-inositol-1,2,5,6-tet-rakisphosphate, D-inositol-1,2,6-trisphosphate, D-inositol-1,2-bisphosphate, D-inositol-1-phosphate; and D-inositol-1,2,4,5,6-pentakisphosphate, D-inositol-1,2,5,6-tetrakisphosphate, D-inositol-1,5,6-trisphosphate. The first pathway is similar to that previously known, while the other one is a new pathway. Isotope results show that the cleavage of the P-O bond during phytate degradation is accompanied by the introduction of one O atom solely from water to the released inorganic orthophosphate. Interestingly, isotopic compositions of all phosphate moieties in K phytate used in this study were found to be the same. This means that the original source of phytate can be tracked from its partially dephosphorylated products. Overall, these results provide improved insights into the mechanisms and pathways of phytate degradation and highlight the importance of an isotopic tool that can potentially be used for tracking phytate source and its degradation products in the environment.
AB - Phytate, the salt of myo-inositol hexakisphosphate, and its partially dephos-phorylated products are commonly present in the environment, but their origins and bioavailability are not well understood. This research applied phosphate O isotope ratios (δ18Op) in combination with nuclear magnetic resonance (NMR) and high-performance liquid chromatography (HPLC) methods to characterize the kinetics and pathways of phytate degradation by wheat phytase and the O isotopic composition during progressive degradation of phytate. Our results show that phytate degradation undertakes two pathways: D-inositol-1,2,3,5,6-pentakisphosphate, D-inositol-1,2,5,6-tet-rakisphosphate, D-inositol-1,2,6-trisphosphate, D-inositol-1,2-bisphosphate, D-inositol-1-phosphate; and D-inositol-1,2,4,5,6-pentakisphosphate, D-inositol-1,2,5,6-tetrakisphosphate, D-inositol-1,5,6-trisphosphate. The first pathway is similar to that previously known, while the other one is a new pathway. Isotope results show that the cleavage of the P-O bond during phytate degradation is accompanied by the introduction of one O atom solely from water to the released inorganic orthophosphate. Interestingly, isotopic compositions of all phosphate moieties in K phytate used in this study were found to be the same. This means that the original source of phytate can be tracked from its partially dephosphorylated products. Overall, these results provide improved insights into the mechanisms and pathways of phytate degradation and highlight the importance of an isotopic tool that can potentially be used for tracking phytate source and its degradation products in the environment.
KW - Abbreviations: HPLC
KW - High-performance liquid chromatography
KW - Inorganic (ortho)phosphate
KW - Inositol phosphate
KW - IP
KW - NMR
KW - Nuclear magnetic resonance
KW - Organic phosphorus
KW - Oxygen isotope ratios
KW - P
KW - P
KW - Ultraviolet radiation
KW - UVR
KW - Vienna standard mean ocean water
KW - VSMOW
KW - δ0
UR - http://www.scopus.com/inward/record.url?scp=84951190774&partnerID=8YFLogxK
U2 - 10.2136/sssaj2015.01.0002
DO - 10.2136/sssaj2015.01.0002
M3 - Article
AN - SCOPUS:84951190774
SN - 0361-5995
VL - 79
SP - 1615
EP - 1628
JO - Soil Science Society of America Journal
JF - Soil Science Society of America Journal
IS - 6
ER -