Phytate Metabolism with Special Reference to its Myo-Inositol Component

Loewus, Frank A.

doi:10.1007/978-1-4684-1167-6_9

Cited by 7 publications

(5 citation statements)

References 51 publications

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“…Clearly, the first three substrates are best. lL-MI-l-P has metabolically significant roles in plants such as intermediate in the MI oxidation pathway and in phytic acid biosynthesis (14,15). Hallcher and Sherman (I 1) found ID-MI-I-P in brain tissue where it too may have a metabolic role.…”

Section: Discussionmentioning

confidence: 99%

Further Studies on myo-Inositol-1-phosphatase from the Pollen of Lilium longiflorum Thunb

Gumber

Loewus²,

Loewus³

1984

Plant Physiol.

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myo-Inositol-l-phosphatase has been purified to homogeneity from Lilium longiflorum pollen using an alternative procedure which includes pH change and phenyl Sepharose column chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis shows that the enzyme is a dimer (subunit molecular weight, 29,000 daltons). The enzyme is stable at low pH values and is inactivated only below pH 3.0. In addition to IL-and ID-myo-inositol-l-phosphate, it shows high specificity for IL-chiro-inositol-3-phosphate. As MI-I -phosphatase2 from lily pollen readily hydrolyzes the enantiomeric forms of MI-1-P (16) and in this respect resembles similar MI-1-phosphatases from yeast (4), rat testis (7), and bovine brain (11). It also hydrolyzes MI-2-P as does the MI-I-P phosphatase from chick erythrocytes (20). In so far as all these Mg2"-dependent, alkaline phosphatases have been examined, their molecular and catalytic properties are quite similar; the notable exception being specificity toward MI-2-P as substrate (16).Here, we describe an alternative method for purification to homogeneity of MI-I -phosphatase from lily pollen and.examine subunit structure, substrate specificity, response to inhibitors, and stability of enzyme to heat and pH. Studies on sulfhydryl involvement at the active site are also presented. MATERIALS AND METHODSChemicals. fl-Glycerol-P, i-glucose-6-P, i-glucitol-6-P, Dmannitol-6-P, phenyl Sepharose and polyethylene glycol (P-2139) were purchased from Sigma Chemical Co. PHMB, NEM, and 2-mercaptoethanol were purchased from Aldrich Chemical 'Supported in part by Grant GM-22427 Purification of MI-1-Phosphatase. The procedure previously described (16) was used through the heat treatment step that followed DEAE-cellulose chromatography to obtain a partially purified MI-I -phosphatase. The DEAE-cellulose step was slightly modified in that the enzyme-loaded DEAE-cellulose column was washed with 0.12 M NaCl in Tris-acetate buffer (300 ml) prior to gradient elution. This pregradient wash removed considerable inactive protein previously encountered in gradient fractions. The gradient was initiated with buffer containing 0.12 M NaCl instead of 0.10 M NaCl as previously described.Heat-treated enzyme (80 ml, 60°C, 20 min) was dialyzed against 10 mm citrate buffer (2 L, pH 3.5) overnight at 4°C. The dialyzed suspension was centrifuged (25,000g, 15 min, 4°C) to remove precipitated protein. NaCl was added to a final concentration of 0.5 M. The enzyme was loaded on a phenyl Sepharose column (8 x 0.6 cm) which had been preequilibrated with 0.5 M NaCl in Tris-acetate. The column was washed with 0.1 M NaCl in Tris-acetate buffer (25 ml) and then the enzyme was eluted with straight buffer. Active fractions were pooled, concentrated by osmodialysis with polyethylene glycol (average mol wt 8,000) to 5 ml, loaded on a column of Ultrogel AcA 34 (90 x 1.2 cm), and washed with 50 mM Tris-acetate, pH 8.0 (150 ml). The MI-I-phosphatase obtained from this column was homogenous by electrophoretic standards. Enzy...

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Section: Discussionmentioning

confidence: 99%

Further Studies on myo-Inositol-1-phosphatase from the Pollen of Lilium longiflorum Thunb

Gumber

Loewus²,

Loewus³

1984

Plant Physiol.

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“…Conclusive proof will require isolation ofthese putative storage bodies followed by biochemical analysis. as has been done for globoids of rice and wheat grain (11,25).…”

Section: Discussionmentioning

confidence: 99%

“…Phytic acid is known to be present as a phosphorus reserve in L. longiflorum pollen (11,22). EDX data and ultrastructural features implicate the inclusion-containing bodies of lily pollen as the storage organelle of phytin.…”

Section: Discussionmentioning

confidence: 99%

Localization of Phosphorus and Cation Reserves in Lilium longiflorum Pollen

Baldi¹,

Franceschi²,

Loewus³

1987

Plant Physiol.

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Transmission electron microscopy of pollen from Lilium longiflorum Thunb. reveals electron-dense inclusions in storage body organelles ubiquitous in the cytosol. In ungerminated pollen, these inclusions are rounded in appearance and appressed to the inner surface of the smooth membrane of the storage body. During pollen germination, these inclusions become less rounded, smaller, and enclosed in storage bodies that have developed crenated membranes. Energy dispersive x-ray analysis reveals high levels of P, Mg, K, and Ca in the inclusions relative to other regions of the cytosol in which elemental signals can be obtained. The elemental composition and the degradation of inclusions during germination are offered as evidence for storage of phytin in these structures which are thus analogous to phytin storage globoids of seed tissues.

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“…A metabolite linked with carbohydrate biosynthesis is myo-inositol, which in seeds is phosphorylated to phytic acid (inositol hexa kis phosphate). This molecule represents the majority of the phosphorus in legume seeds, serving as phosphorus reservoirs and also as signalling molecules in biotic and abiotic stresses [53,54]. Although inositol phosphates can be considered as antinutrients due to their chelating capacity that reduces the absorption of useful ions such as iron, zinc, magnesium, and calcium [54,55], the chelating abilities have been associated with antioxidant properties, heavy metal toxicity reduction, and amelioration of heart disease [56].…”

Section: Loadings On Sc3mentioning

confidence: 99%

Pisum sativum L. ‘Eso’: Metabolic Profiling of Yellow Seeds to Define the Optimal Harvest Time

Patriarca,

Sciubba,

Tomassini

et al. 2024

Agriculture

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The yellow pea (Pisum sativum L. ‘Eso’, sin. Lathyrus oleracaeus Lam.(YP)) is an annual herbaceous plant that belongs to the Fabaceae family. Peas, along with other legumes, are an excellent source of proteins and essential amino acids; the yellow variety is known for maintaining a good protein profile even if subjected to industrial processing. However, the presence of antinutrients, such as phytates and oligosaccharides, limits its consumption as a fresh legume to its use as a source of isolated proteins or for animal feed. The aim of the study is to evaluate the changes in the entire phytochemical profile of YP seeds as a function of the harvest time. YPs harvested at about 40, 50, 60, and 70 days from sowing were examined by high-resolution NMR spectroscopy employing 1H-NMR, 1H-1H TOCSY, and 1H-13C HSQC. In total, 40 molecular species were identified and quantified; it was observed that there was a monotonous decrease in amino acids, carbohydrates, and secondary metabolites as a function of time. Antinutrient levels increased, but only in later sampling times. This study identified the optimal harvest time for yellow peas “Eso” in the fortieth day from sowing, adding new information about the best nutritional outcome for humans.

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Phytate Metabolism with Special Reference to its Myo-Inositol Component

Cited by 7 publications

References 51 publications

Further Studies on myo-Inositol-1-phosphatase from the Pollen of Lilium longiflorum Thunb

Further Studies on myo-Inositol-1-phosphatase from the Pollen of Lilium longiflorum Thunb

Localization of Phosphorus and Cation Reserves in Lilium longiflorum Pollen

Pisum sativum L. ‘Eso’: Metabolic Profiling of Yellow Seeds to Define the Optimal Harvest Time

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