Oxalate Synthesis Research Articles

Diet and the frequency of the alanine:glyoxylate aminotransferase Pro11Leu polymorphism in different human populations.

The intermediary metabolic enzyme alanine:glyoxylate aminotransferase (AGT) contains a Pro11Leu polymorphism that decreases its catalytic activity by a factor of three and causes a small proportion to be mistargeted from its normal intracellular location in the peroxisomes to the mitochondria. These changes are predicted to have significant effects on the synthesis and excretion of the metabolic end-product oxalate and the deposition of insoluble calcium oxalate in the kidney and urinary tract. Based on the evolution of AGT targeting in mammals, we have previously hypothesised that this polymorphism would be advantageous for individuals who have a meat-rich diet, but disadvantageous for those who do not. If true, the frequency distribution of Pro11Leu in different extant human populations should have been shaped by their dietary history so that it should be more common in populations with predominantly meat-eating ancestral diets than it is in populations in which the ancestral diets were predominantly vegetarian. In the present study, we have determined frequency of Pro11Leu in 11 different human populations with divergent ancestral dietary lifestyles. We show that the Pro11Leu allelic frequency varies widely from 27.9% in the Saami, a population with a very meat-rich ancestral diet, to 2.3% in Chinese, who are likely to have had a more mixed ancestral diet. FST analysis shows that the differences in Pro11Leu frequency between some populations (particularly Saami vs Chinese) was very high when compared with neutral loci, suggesting that its frequency might have been shaped by dietary selection pressure.

Synthesis of Dimethyl Oxalate from CO and CH3ONO on Carbon Nanofiber Supported Palladium Catalysts

A series of novel palladium catalysts supported on carbon nanofibers of various nanostructures have been prepared, characterized, and tested in gas-phase synthesis of dimethyl oxalate. Significant improvements in both activity and selectivity have been achieved over well-defined carbon nanofiber supported palladium catalysts. Carbon nanofiber produced on 20% NiFe/Al2O3 (CNF-05) supported palladium catalyst possesses the highest activity, which can be ascribed to the high surface area of the support, relatively weak metal−support interaction, and smaller metal particles. The low metal−support interaction might improve the redox properties of the catalyst, and thus the activity. The functionalization of CNF-05 in air is found to dramatically increase the conversion of methyl nitrite compared to the functionalization in HNO3.

Effect of ammonium application on the oxalate content of tea plants (Camellia sinensis L.)

Tea plants (Camellia sinensis L.) were hydroponically cultured for 9 d in a solution containing ammonium as a sole nitrogen source (0 (control), 50, 100, or 200 mg N L-1 ), and harvested after 0 (control), 1,3,6, and 9 d of treatments to investigate the effect of ammonium on the content and metabolism of oxalate in tea plants. Total and water-soluble oxalate contents in young leaves and roots treated with 50, 100, and 200 mg N L-1 decreased in proportion to the amount of ammonium applied, with levels significantly lower than those without ammonium application. In old leaves, both total and water-soluble oxalate contents showed constant values during the treatment period. The content of total ascorbic acid (AsA) in young leaves increased with the amount of ammonium in the medium. The activity of oxalate oxidase (OxO) in young leaves also increased with the concentration of ammonium in the medium and with the duration of the treatment. However, in roots, total AsA content and OxO activity were not affected. These results suggest that in young tea leaves, the application of ammonium suppressed the synthesis of oxalate via AsA oxidation and stimulated the decomposition of oxalate by the increase of the OxO activity, resulting in the accumulation of AsA and a decrease in oxalate content. On the other hand, in old leaves and young roots, the responses to ammonium were different from those in young leaves, suggesting that the oxalate metabolism may be controlled by different mechanisms in different parts of the tea plants.

Effect of CO2 Enrichment on Oxalate Synthesis, Plant Growth and Biochemistry of "Actinidia" Plantlets.

Effect of CO2 Enrichment on Oxalate Synthesis, Plant Growth and Biochemistry of "Actinidia" Plantlets.

Oxalate coprecipitation synthesis and transport properties of polycrystalline Sr1−xLaxPbO3−δ solid solutions

Solid solutions Sr1−xLaxPbO3−δ with x=0, 0.05, 0.1, 0.15, 0.2 and 0.25 were synthesized by oxalate precursor coprecipitation methods. The solid solutions obtained were analyzed by the XRD technique and iodometric titration. Resistivity ρ and thermoelectric power S were measured for temperatures 20K<T<300K. The parent compound SrPbO3−δ shows a shallow minimum of ρ(T) at about 120K, whereas ρ(T) for the La-doped samples are rather smooth with weakly manifested inflection points for all investigated compositions. The thermoelectric power is negative. The transport data demonstrate that the ceramic samples Sr1−xLaxPbO3−δ are unstable towards electron spectrum dielectrization or localization of current carriers. From the analysis of the measured properties it may be inferred that the effects of disorder and granularity and the inter-grain tunneling, in particular, strongly influence transport phenomena.

Hydrothermal synthesis and characterization of the first oxalate–bta mixed-ligand three-dimensional frameworks: {[M2(µ8-bta)(µ2-C2O4)]·(H3O)2(H2O)2}n (M = CoII, FeII; bta = benzene-1,2,4,5-tetracarboxylate)

Two new metal–organic complexes formulated as {M2(μ8-bta)(μ2-C2O4)·(H3O)2(H2O)2}n (1: M = CoII; 2: M = FeII; bta = benzene-1,2,4,5-tetracarboxylate) have been hydrothermally synthesized at 160 °C for 120 h. Their structures were determined by single-crystal X-ray diffraction analysis and characterized by XPS, IR, ICP, elemental, TG and magnetic analysis. Complexes 1 and 2 are isostructural and represent the first coordination network structure constructed by bridging oxalate and bta mixed ligands. In the crystallographic independent unit each metal ion center is in a distorted octahedral geometry and coordinated by four O atoms from the four COO groups of four bta ligands and by two other O atoms from a bis-chelating oxalate ligand. The interconnected independent units create different types of channels running in different directions. The complexes 1 and 2 contain helical chains composed of left-handed and right-handed helices interlaced in pairs. Uncoordinated water molecules occupy the channels in the two complexes. Both of the complexes have intramolecular antiferromagnetic interactions.

Hepatic Alanine-glyoxylate Aminotransferase Activity and Oxalate Metabolism in Vitamin B6 Deficient Rats

Hepatic Alanine-glyoxylate Aminotransferase Activity and Oxalate Metabolism in Vitamin B6 Deficient Rats

Hydrothermal synthesis of an open-framework manganese oxalate incorporating KCl chains

A manganese oxalate of the composition, K 2[Mn 2(C 2O 4) 3]2[KCl]·2H 2O, containing metal oxalate layers connected by monodentate oxalate units has been synthesized hydrothermally. An unique feature of this material is that it contains KCl chains with a KCl distance of ∼3.2 Å, close to the value in bulk KCl.

A metabolic role of the glyoxylate and tricarboxylic acid cycles for development of the copper-tolerant brown-rot fungus Fomitopsis palustris.

Fruit bodies of the copper-tolerant brown-rot fungus Fomitopsis palustris were produced in liquid medium for the first time. To induce fruit body formation of this fungus, it was important to inoculate the liquid medium with mycelia grown on potato dextrose agar plates and also to adjust the initial pH of the medium to 5.0. The metabolic role of the glyoxylate and tricarboxylic acid cycles during fungal development in the liquid culture was investigated in relation to oxalate biosynthesis. The enzymes for the glyoxylate cycle and oxalate biosynthesis in mycelium showed greater activities at the vegetative growth stage than at the fruiting stage. The ratios of isocitrate dehydrogenase activity to isocitrate lyase activity in mycelium were 0.3 and 4.0 at the vegetative and fruiting stage, respectively. Thus, isocitrate lyase of the glyoxylate cycle played a more important role in oxalate synthesis at the earlier stage of the cultivation, whereas isocitrate dehydrogenase played a major role in glutamate synthesis during fruit body formation.

A metabolic role of the glyoxylate and tricarboxylic acid cycles for development of the copper-tolerant brown-rot fungus Fomitopsis palustris

Fruit bodies of the copper-tolerant brown-rot fungus Fomitopsis palustris were produced in liquid medium for the first time. To induce fruit body formation of this fungus, it was important to inoculate the liquid medium with mycelia grown on potato dextrose agar plates and also to adjust the initial pH of the medium to 5.0. The metabolic role of the glyoxylate and tricarboxylic acid cycles during fungal development in the liquid culture was investigated in relation to oxalate biosynthesis. The enzymes for the glyoxylate cycle and oxalate biosynthesis in mycelium showed greater activities at the vegetative growth stage than at the fruiting stage. The ratios of isocitrate dehydrogenase activity to isocitrate lyase activity in mycelium were 0.3 and 4.0 at the vegetative and fruiting stage, respectively. Thus, isocitrate lyase of the glyoxylate cycle played a more important role in oxalate synthesis at the earlier stage of the cultivation, whereas isocitrate dehydrogenase played a major role in glutamate synthesis during fruit body formation.

The Role of Peroxisomes in the Integration of Metabolism and Evolutionary Diversity of Photosynthetic Organisms

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis and structure of a zinc oxalate with honeycomb layers and zinc phosphates with one- and three-dimensional structures

Three new compounds, a zinc oxalate I, [(CH 3) 2NH(CH 2) 3NH 3][Zn 2(C 2O 4) 3]·2H 2O, and two zinc phosphates II, [(CH 3) 2NH(CH 2) 3NH 3][Zn(HPO 4) 2]·H 2O, and III, [(CH 3) 2NH(CH 2) 3NH 3][(ZnPO 4) 2]·2H 2O, have been synthesized by solvothermal reactions in the presence of N,N-dimethyl-1,3-diaminopropane. While I has a honeycomb zinc oxalate layers with 12-membered apertures (6 Zn and 6 oxalates), II has a one-dimensional corner-shared 4-membered ring (Zn 2P 2O 4) zinc phosphate chains, and III has a three-dimensional zinc phosphate structure. The structure of III resembles the aluminosilicate zeolite, thomsonite. The formation of these open-framework solids appears to depend on the relative concentrations of the amine and phosphoric acid in the synthesis mixture.

Nitrate and oxalate contents of tea plants (Camellia sinensis L.) with special reference to types of green tea and effect of shading

To analyze the utilization of nitrate and synthesis of oxalate in tea plants Camellia sinensis L., differences in nitrate and oxalate contents in different parts (flushes, leaves, stems, and roots) and in four types of Japanese green tea (normally steamed and heavily steamed Sencha, Gyokuro, and Tencha) were examined. Nitrate content was high only in fibrous roots (0.25 g NO3 − kg−1 DW) and very low in other parts (< 0.06 g NO3 − kg−1 DW). The highest content of water-soluble oxalate was detected in flushes, whereas that of crystal oxalate (calcium oxalate) in mature leaves. Oxalate was also detected in the xylem sap. These findings suggest that oxalate, synthesized at the time of nitrate reduction in fibrous roots, is transported to flushes and leaves and then accumulates in mature leaves as crystal oxalate. There were no significant differences between the nitrate and oxalate contents of the normally steamed and heavily steamed types of Sencha, which were produced by steaming for 30 to 60 s and for 60 to 180 s, respectively. The contents of nitrate and oxalate of Gyokuro and Tencha, which were cultivated with shading, were higher than those of Sencha, which was cultivated without shading. These results suggest that shading affects the nitrate and oxalate contents of tea flushes. Nitrate and oxalate contents gradually increased in the flushes with shading but remained almost constant in the flushes without shading. At the end of the shading treatment, the nitrate content per unit field area in the flushes with shading was approximately 4-times higher than that in the flushes without shading. On the other hand, the oxalate amounts per unit field area in both flushes with and without shading increased at the same rates, indicating that the oxalate content per dry weight decreased along with growth. The ratio of oxalate content to reduced N content in the flushes under shading was higher than that in the flushes without shading. These results indicate that shading increased the nitrate content by the repression of the nitrate reductase activity and that oxalate was synthesized not only by nitrate reduction but also via other pathways.

Potential mechanisms of marked hyperoxaluria not due to primary hyperoxaluria I or II

Hyperoxaluria may be idiopathic, secondary, or due to primary hyperoxaluria (PH). Hepatic alanine:glyoxylate aminotransferase (AGT) or glyoxylate/hydroxypyruvate reductase (GR/HPR) deficiency causes PHI or PHII, respectively. Hepatic glycolate oxidase (GO) is a candidate enzyme for a third form of inherited hyperoxaluria. Six children were identified with marked hyperoxaluria, urolithiasis, and normal hepatic AGT (N = 5) and GR/HPR (N = 4). HPR was below normal and GR not measured in one. Of an affected sibling pair, only one underwent biopsy. GO mutation screening was performed, and dietary oxalate (Diet(ox)), enteric oxalate absorption (EOA) measured using [13C2] oxalate, renal clearance (GFR), fractional oxalate excretion (FE(ox)) in the children, and urine oxalate in first-degree relatives (FDR) to understand the etiology of the hyperoxaluria. Mean presenting age was 19.2 months and urine oxalate 1.3 +/- 0.5 mmol/1.73 m2/24 h (mean +/- SD). Two GO sequence changes (T754C, IVS3 - 49 C>G) were detected which were not linked to the hyperoxaluria. Diet(ox) was 42 +/- 31 mg/day. EOA was 9.4 +/- 3.6%, compared with 7.6 +/- 1.2% in age-matched controls (P = 0.33). GFR was 90 +/- 19 mL/min/1.73 m2 and FE(ox) 4.2 +/- 1.4. Aside from the two brothers, hyperoxaluria was not found in FDR. These patients illustrate a novel form of hyperoxaluria and urolithiasis, without excess Diet(ox), enteric hyper-absorption, or hepatic AGT, GR/HPR deficiency. Alterations in pathways of oxalate synthesis, in liver or kidney, or in renal tubular oxalate handling are possible explanations. The affected sibling pair suggests an inherited basis.

Decreased Renal Expression of the Putative Calcium Oxalate Inhibitor Tamm-Horsfall Protein in the Ethylene Glycol Rat Model of Calcium Oxalate Urolithiasis.

Tamm-Horsfall protein is believed to inhibit calcium oxalate crystallization, aggregation or adhesion to the renal epithelium. We determined whether ethylene glycol induced urolithiasis changes the expression of renal and urinary Tamm-Horsfall protein. For comparison the expression of another calcium oxalate inhibitor, osteopontin, was also analyzed. Male rats were treated with 0.75% ethylene glycol plus an AIN-76 diet (Dyets, Bethlehem Pennsylvania) (ethylene glycol group) or standard rat chow and water (control group) for up to 8 weeks (6 per group for 8 weeks and 3 per group for 3 days to 6 weeks). Kidneys and urine (8 weeks only) were harvested and analyzed by Northern and Western blot analysis, and immunohistochemistry. Tamm-Horsfall protein message and protein (membrane bound form) were decreased, while those of osteopontin were increased in the kidneys of rats treated with ethylene glycol for 8 weeks. As judged by immunochemistry Tamm-Horsfall protein and osteopontin were consistently present in a few tubules in rats in the ethylene glycol and control groups, respectively. In urine expression of the free form of Tamm-Horsfall protein (approximately 75 kDa.) was decreased but detectable in ethylene glycol treated rats. Although readily detected in tissue, osteopontin was not detected in the urine of control or ethylene glycol treated rats. In the time course experiment Tamm-Horsfall protein did not decrease until 4 weeks, when calcium oxalate crystals were detectable in the kidneys of treated rats. In contrast, osteopontin was increased, although inconsistently, beginning at 3 days. Unlike other calcium oxalate inhibitors, such as osteopontin, renal message and protein for Tamm-Horsfall protein was decreased in ethylene glycol treated rats. Tamm-Horsfall protein expression did not decrease until aggregates of crystals had been deposited in the kidneys, while osteopontin expression began to increase almost immediately. Comparisons of the data on kidneys and urine obtained by RNA or protein blot analysis and immunochemistry underscore the need to examine tissue and urine by multiple techniques to obtain the most accurate assessment of how protein expression is changed by a given treatment.

A Reactive Intermediate in the Synthesis of Iron Arsenates: Synthesis of the First One-Dimensional Iron Arsenate Oxalate and Its Transformation into Two- and Three-Dimensional Iron Arsenates

A Reactive Intermediate in the Synthesis of Iron Arsenates: Synthesis of the First One-Dimensional Iron Arsenate Oxalate and Its Transformation into Two- and Three-Dimensional Iron Arsenates

A reactive intermediate in the synthesis of iron arsenates: synthesis of the first one-dimensional iron arsenate oxalate and its transformation into two- and three-dimensional iron arsenates.

Three-dimensions from one: One-dimensional iron arsenate oxalate is prepared, and shown to be reactive, giving rise to a two- and a mixed-valent (FeIII/FeII) three-dimensional iron arsenate structure (see picture). The sequential crystallization provides evidence for the building up of open architectures from low to higher dimensional structures, demonstrating the “life of a chemical system”.

共沈法を用いた廃蛍光体スラッジからの赤色蛍光体（Ｙ２Ｏ３ ： Ｅｕ｀３＋´）の合成

The coprecipitation behaviors of leaching solution and their sintering conditions have been examined to synthesize red phosphor (Y2O3:Eu3+) from phosphor sludge contained in waste fluorescent lamp. At first, the recovery of rare earth elements and the removal of impurity in the leaching solution were investigated by treatment processes such as hydroxide and oxalate precipitations. The drying process of coprecipitation reaction product was examined by freeze-dry and air-dry. The synthesis behavior of red phosphor (Y2O3:Eu3+) was also investigated by changing some factors such as temperature, time and flux. The experimental results obtained are summarized as follows:(1) The homogeneous Y and Eu oxalate precipitations were produced by adding oxalic acid into leaching solution under the dispersion using ultrasonic stirring and the desiccation using freeze-dry.(2) Y and Eu precipitations were sintered at 1,473 K for 144 ks under the addition of 1 % barium borate as a flux. Red phosphor (Y2O3:Eu3+) sintered had crystal size more than 0.2μm and average particle size of 5-6μm.(3) Impurity elements in leaching solution were efficiently removed by hydroxide precipitation process, in which leaching solution was retained at less than pH 5.0 and by oxalate synthesis process, in which oxalic acid was added to use 3 times the molar quantity of Y and Eu hydroxides. In these treatments, recovery of Y and Eu were about 85 %, respectively.(4) Synthesis process of red phosphor (Y2O3:Eu3+) from waste phosphor sludge contained in fluorescent lamp was established by using simulate leaching solution. On the basis of these treatment methods, rare earth powder of red phosphor was synthesized from waste phosphor sludge.Luminescence properties of rare earth powder synthesized were in fairly agreement with these of commercial red phosphor. Rare earth powder synthesized in this work may be used substantially as a red phosphor.

Molecular Basis for the Dual Mitochondrial and Cytosolic Localization of Alanine:Glyoxylate Aminotransferase in Amphibian Liver Cells

To gain further insights into the molecular basis of the evolution of alanine:glyoxylate aminotransferase (AGT) intracellular targeting in vertebrates, we have studied the molecular basis of its dual mitochondrial and cytosolic distribution in amphibian liver cells. The AGT gene in Xenopus laevis encodes a polypeptide of 415 amino acids, which includes a 24-residue N-terminal mitochondrial targeting sequence (MTS), at either end of which are located two in-frame potential translation start sites. This MTS is necessary to target Xenopus AGT and sufficient to target a green fluorescent fusion protein to mitochondria in transfected COS cells. The C-terminal tripeptide (KKM), despite being similar to the nonconsensus type 1 peroxisomal targeting sequence in human AGT (KKL), was unable to target Xenopus AGT or human AGT to peroxisomes. The Xenopus AGT gene produces two types of transcript. The longer form encodes a polypeptide that contains the MTS and is targeted to mitochondria. The shorter form encodes a polypeptide that does not contain the MTS and remains in the cytosol. These results are discussed not only in terms of the molecular evolution of AGT targeting but also in terms of the ancillary requirements for the peroxisomal targeting of human AGT.

Simplified chemical route for the synthesis of barium titanyl oxalate (BTO)

A simple chemical route is developed to obtain an important molecular precursor (leading to barium titanate powders), namely barium titanyl oxalate (BTO) with nearly theoretical yield. In this route, 0.1 M alcoholic solution of titanium tetrabutoxide is reacted with 0.1 M alcoholic solution of oxalic acid to form titanyl oxalate (TiOC2O4). This was further converted to soluble ammonium titanyl oxalate (ATO); (NH4)2TiO(C2O4)2.H2O by reacting with an equimolar aqueous solution of ammonium oxalate (pH 4.25). Instead of using available barium salts (halide/nitrate/acetate) solution, a modified barium precursor solution with controlled pH (=4.2) is prepared for carrying out cation-exchange reaction with ATO. For this purpose the modified Ba-precursor solution is freshly prepared by partial neutralization of a 0.1 M aqueous solution of barium hydroxide with controlled addition of dilute HNO3 (1.1 M) solution. The pH of this solution is the same as that of the ATO solution. The exchange reaction between equimolar ATO and modified Ba-precursor solution precipitated barium titanyl oxalate (BTO) with a quantitative yield at room temperature. Submicron-sized, stoichiometric, pure BaTiO3 powders were obtained by the controlled pyrolysis of BTO in air. The present communication deals with the detailed analysis of this simplified method in producing BTO/BT powders and their characterization employing various physicochemical techniques.