TY - JOUR
T1 - Inositol phosphates from barley low-phytate grain mutants analysed by metal-dye detection HPLC and NMR
AU - Hatzack, F.
AU - Hübel, F.
AU - Zhang, W.
AU - Hansen, P. E.
AU - Rasmussen, S. K.
PY - 2001/3/1
Y1 - 2001/3/1
N2 - Inositol phosphates from barley low-phytate grain mutants and their parent variety were analysed by metal-dye detection HPLC and NMR. Compound assignment was carried out by comparison of retention times using a chemical hydrolysate of phytate [Ins(1,2,3,4,5,6)P6] as a reference. Co-inciding retention times indicated the presence of phytate, D/L-Ins(1,2,3,4,5)P5, Ins(1,2,3,4,6)P5, D/L-(1,2,4,5,6)P5, D/L-(1,2,3,4)P4. D/L-Ins-(1,2,5,6)P4 and D/L-Ins(1,4,5,6)P4 in PLP1B mutants as well as the parent variety. In grain extracts from mutant lines PLP1A, PLP2A and PLP3A unusual accumulations of D/L-Ins(1,3,4,5)P4 were observed whereas phytate and the above-mentioned inositol phosphates were present in relatively small amounts. Assignment of D/L-Ins(1,3,4,5)P4 was corroborated by precise co-chromatography with a commercial Ins(1,3,4,5)P4 standard and by NMR spectroscopy. Analysis of inositol phosphates during grain development revealed accumulation of phytate and D/L-Ins(1,3,4,5)P4, which suggested the tetrakisphosphate compound to be an intermediate of phytate synthesis. This assumption was strengthened further by phytate degradation assays showing that D/L-Ins(1,3,4,5)P4 did not belong to the spectrum of degradation products generated by endogenous phytase activity. Metabolic scenarios leading to accumulation of D/L-Ins(1,3,4,5)P4 in barley low-phytate mutants are discussed.
AB - Inositol phosphates from barley low-phytate grain mutants and their parent variety were analysed by metal-dye detection HPLC and NMR. Compound assignment was carried out by comparison of retention times using a chemical hydrolysate of phytate [Ins(1,2,3,4,5,6)P6] as a reference. Co-inciding retention times indicated the presence of phytate, D/L-Ins(1,2,3,4,5)P5, Ins(1,2,3,4,6)P5, D/L-(1,2,4,5,6)P5, D/L-(1,2,3,4)P4. D/L-Ins-(1,2,5,6)P4 and D/L-Ins(1,4,5,6)P4 in PLP1B mutants as well as the parent variety. In grain extracts from mutant lines PLP1A, PLP2A and PLP3A unusual accumulations of D/L-Ins(1,3,4,5)P4 were observed whereas phytate and the above-mentioned inositol phosphates were present in relatively small amounts. Assignment of D/L-Ins(1,3,4,5)P4 was corroborated by precise co-chromatography with a commercial Ins(1,3,4,5)P4 standard and by NMR spectroscopy. Analysis of inositol phosphates during grain development revealed accumulation of phytate and D/L-Ins(1,3,4,5)P4, which suggested the tetrakisphosphate compound to be an intermediate of phytate synthesis. This assumption was strengthened further by phytate degradation assays showing that D/L-Ins(1,3,4,5)P4 did not belong to the spectrum of degradation products generated by endogenous phytase activity. Metabolic scenarios leading to accumulation of D/L-Ins(1,3,4,5)P4 in barley low-phytate mutants are discussed.
KW - Grain filling
KW - Hordeum vulgare
KW - Inositol phosphate kinase
KW - Phytase
KW - Seed-specific
UR - http://www.scopus.com/inward/record.url?scp=0035282067&partnerID=8YFLogxK
U2 - 10.1042/0264-6021:3540473
DO - 10.1042/0264-6021:3540473
M3 - Journal article
C2 - 11171128
AN - SCOPUS:0035282067
SN - 0264-6021
VL - 354
SP - 473
EP - 480
JO - Biochemical Journal
JF - Biochemical Journal
IS - 2
ER -