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PubMed2005

Homology modelling of the major peanut allergen Ara h 2 and surface mapping of IgE-binding epitopes.

Three-dimensional models built for the peanut Ara h 2 allergen and other structurally-related 2S albumin allergens of dietary nuts exhibited an overall three-dimensional fold stabilized by disulphide bridges well conserved among all the members of the 2S albumin superfamily. Conformational analysis of the linear IgE-binding epitopes mapped on the molecular surface of Ara h 2 showed no structural homology with the corresponding regions of the walnut Jug r 1, the pecan nut Car i 1 or the Brazil nut Ber e 1 allergens. The absence of epitopic community does not support the allergenic cross-reactivity observed between peanut and walnut or Brazil nut, which presumably depends on other ubiquitous seed storage protein allergens, namely the vicilins. However, the major IgE-binding epitope identified on the molecular surface of the walnut Jug r 1 allergen shared a pronounced structural homology with the corresponding region of the pecan nut Car i 1 allergen. With the exception of peanut, 2S albumins could thus account for the IgE-binding cross-reactivity observed between some other dietary nuts, e.g. walnut and pecan nut.

2S Albumins, Plant↗
PubMed2005

Purification and cloning of two high molecular mass isoforms of peanut seed oleosin encoded by cDNAs of equal sizes.

Oleosins are small plant proteins characterized by a long hydrophobic core flanked by amphipathic N- and C-terminal domains, which act as emulsifiers for the storage of lipids in seeds. They have been sequenced in a number of oilseeds important for the food industry but not in peanuts. We purified the major isoform of peanut oleosin by preparative electrophoresis with continuous elution, in sufficient amounts to raise specific antibodies, perform circular dichroism and N-sequence tryptic fragments. The structure of the purified oleosin was dominated by alpha-helix that may be assigned to the SDS-resistant central hydrophobic stretch. A two-step RT-PCR strategy was developed to determine the cDNA sequence of this oleosin. Two cDNA variants of equal sizes encoding for isoforms of 176 amino acids each were identified. The isoforms differed by seven amino acids mainly located in the N- and C-terminal domains. The corresponding mRNAs were estimated at 0.9 kb by Northern blot and were transcribed from genes without introns. Immunoprecipitation of the in vitro-translated peanut oleosin labeled with [14C]leucine or [35S]methionine produced the full-length protein (17 kDa) and a 6-kDa peptide corresponding to the N/C-terminal domains. This peptide was able to form SDS-PAGE stable oligomers by interacting with the full-length protein. A similar peptide was released after [125I]iodination of the purified oleosin that generated intermediate-sized oligomers also visible by Western blot on a crude oleosin extract. Oligomers reflect the natural ability of oleosins to strongly interact with each other via not only their central domains but also their N- and C-terminal domains.

Amino Acid Sequence↗
PubMed1996

The crystal structure of peanut peroxidase.

BACKGROUND: Peroxidases catalyze a wide variety of peroxide-dependent oxidations. Based on sequence alignments, heme peroxidases have been divided into three classes. Crystal structures are available for peroxidases of classes I and II, but until now no structure has been determined for class III, the classical extracellular plant peroxidases. RESULTS: The crystal structure of peanut peroxidase has been solved to 2.7 A resolution. The helical fold is similar to that of known peroxidase structures. The 294-residue polypeptide chain is accompanied by a heme and two calcium ions, and there is some evidence of glycosylation. CONCLUSIONS: This is the first complete structure of a class III peroxidase and as such should serve as a model for other class III enzymes including the much-studied horseradish peroxidase. It may also aid in the interpretation of functional differences between the peroxidase classes. Ten helices conserved in class I and II peroxidases are also found in peanut peroxidase. Key residues of the heme environment and the location of two calcium ions are shared with class II peroxidases. Peanut peroxidase contains three unique helices, two of which contribute to the substrate access channel leading to the heme edge.

Amino Acid Sequence↗
PubMed1994

Magnetic resonance imaging for aspirated peanut in the bronchus.

Peanut inhalation in the right main bronchus of a 15-month-old boy was diagnosed using a T1-weighted image produced by magnetic resonance imaging (MRI) because of the high fat content of the peanut. The T1-weighted MRI image may also be useful in diagnosing other kinds of aspirated nuts with high lipid content as well as peanuts. This method does not involve any X-ray exposure.

Arachis↗
PubMed2001

Accumulation and decay of chlorothalonil and selected metabolites in surface soil following foliar application to peanuts.

One of the principal uses of the fungicide, chlorothalonil, is control of foliar peanut diseases. Recent assessments indicate its runoff from treated fields in southeastern states presents risks to aquatic life. Two factors that control its runoff are how much reaches soil surfaces and degradation rates. To address these questions and to evaluate accumulation and decay of key metabolites, soil samples (0-2 cm) were collected after seven chlorothalonil applications on experimental peanut plots in south central Georgia during the 1999 growing season. At the start of and during laboratory incubations, samples were analyzed for the parent and degradates by HPLC-PDA-APCI-MS. The maximum observed residue levels were after the second application, after which canopy closure reduced soil deposition from later applications to 5-10% of applied amounts. After the last spray, < 5% of the cumulative chlorothalonil applied was detected in the soil. Foliar interception and dissipation and rapid soil degradation contributed to low residue levels. Soil half-lives were < 1-3.5 days for chlorothalonil and 10-22 days for its principal degradate, 4-hydroxychlorothalonil. Other daughter and granddaughter products were detected, some of which accumulated during the growing season. Results emphasize the plant canopy role in controlling the amount of fungicide sprays that reach soil surfaces and suggest concentration-dependent chlorothalonil degradation with degradation rates increasing as soil loading decreases. The study indicates that the 30-day field half-life often used for risk assessments of this pesticide is too long for one of its most important agronomic uses, i.e., in southeastern peanut production. It also indicates that the principal metabolites are more persistent than the parent, and more study is needed to identify and quantify their fate pathways.

Agriculture↗
PubMed2004

Synergic nitrogen source route to inorganic fullerene-like boron nitride with vessel, hollow sphere, onion, and peanut nanostructures.

In this paper we describe the large-scale synthesis of inorganic fullerene-like (IF-like) hexagonal boron nitride with vessel, hollow sphere, peanut, and onion structures by reacting BBr(3) with the synergic nitrogen sources NaNH(2) and NH(4)Cl at 400-450 degrees C for 6-12 h. The composition of products could be confirmed to be pure boron nitride with hexagonal structures by the XRD patterns and FT-IR, XPS, and EDXA spectra. The representative HRTEM images clearly reveal the layerlike features of the products. Here, the peanut-like structure of the IF-like BN is reported for the first time, and added to the list as one kind of new morphology of BN nanomaterials. The similarity in the structure between h-BN and graphite is responsible for the formation of IF-like BN with nanostructures of vessels, hollow spheres, peanuts, and onions.

Journal Article↗
PubMed2003

Identification of an antioxidant, ethyl protocatechuate, in peanut seed testa.

The antioxidant activity and identification of the antioxidant component of peanut seed testa were investigated. The antioxidant activity of peanut seed testa was studied in the linoleic acid model system by using the ferric thiocyanate method. Among the five organic solvent extracts, the ethanolic extracts of peanut seed testa (EEPST) produced higher yields and stronger antioxidant activity than other organic solvent extracts. EEPST was separated into 17 fractions on silica gel column chromatography. Fraction 17, which showed the largest yield and significant antioxidant activity, was separated by thin-layer chromatography. Four major antioxidative subfractions were present. Subfraction 17-2 was found to be effective in preventing oxidation of linoleic acid. This subfraction was further fractionated and isolated and characterized by UV, MS, IR, and (1)H NMR techniques. The active compound was identified as ethyl protocatechuate (3,4-dihydroxybenzoic acid ethyl ester).

Antioxidants↗
PubMed2003

Value assignment of nutrient and aflatoxin concentrations in standard reference material 2387 peanut butter.

Standard Reference Material (SRM) 2387 peanut butter was recently issued, and the process used for value assignment of nutrient and aflatoxin concentrations is reported herein. Values were assigned using data provided by the National Institute of Standards and Technology (NIST) and collaborating laboratories. SRM 2387 is intended for use as a primary material for assigning values to in-house control materials and for validation of analytical methods for measurements in peanut butter and similar high-fat matrixes. SRM 2387 lies in sector 3 of AOAC International's fat-protein-carbohydrate triangle. With the addition of SRM 2387, NIST now offers materials within-or on the borders between-all sectors of the triangle. The Certificate of Analysis for SRM 2387 provides assigned values for concentrations of fatty acids, proximates, elements, and total dietary fiber, for which product labeling is required by the Nutrition Labeling and Education Act of 1990, as well as several vitamins, amino acids, and aflatoxins, for which labeling is not required. (Aflatoxin levels in peanut butter are regulated by the Food and Drug Administration.)

Aflatoxins↗
PubMed2004

Foliar and soil deposition of pesticide sprays in peanuts and their washoff and runoff under simulated worst-case rainfall conditions.

There are few studies that relate the timing and amounts of pesticide washoff from plant foliage during rainfall to runoff losses at the edge of the field. We hypothesized that foliar deposits, if washed onto the soil slowly during rainfall, may then undergo less leaching during the period of infiltration that occurs prior to soil saturation and runoff, thus exhibiting larger runoff losses than pesticides on/in the soil at the beginning of rain. We measured the runoff of ethalfluralin, metolachlor, chlorothalonil, and rhodamine WT dye using simulated rainfall on 450 m2 mesoplots planted in peanut. Ethalfluralin was applied preplant incorporated, and metolachlor was applied preemergence on bare soil. Chlorothalonil and rhodamine WT were applied to the peanut canopy at maturity. Rainfall was simulated 24 h after each chemical application (in May and July, 1998, and May and August, 1999) using raindrop sprinklers, applying 5.5 +/- 0.5 cm over a 2 h period to create reasonable worst-case conditions; between 3 and 9 mm of runoff was generated. Volume-weighted average concentrations of chemicals in runoff were 7, 104, 163, and 179 ug L(-1) for ethalfluralin, metolachlor, chlorothalonil, and rhodamine WT, respectively. The total amounts of chemicals lost in the runoff events were 0.04 +/- 0.01, 0.2 +/- 0.1, 0.6 +/- 0.5, and 0.2 +/- 0.1, as percents of amounts applied, respectively. Rhodamine WT formed a vivid red solution on wetting and provided visual clues to the dynamics of chemical washoff/runoff. The washoff from rain-exposed peanut foliage appeared to be complete within a few minutes of the beginning of rainfall, and disappearance of dye from rain-exposed soil surface occurred within the first 10 min of rainfall. However, dye was present in runoff water at near-constant concentrations throughout the 2 h runoff event, indicating that near-constant amounts of chemical remained in the soil extraction zone. These results confirm earlier studies showing that soil incorporation at application significantly reduces runoff losses and that a majority of foliar residues can be washable if rainfall occurs within a few days after application. Runoff losses of foliar-applied pesticides were small relative to washoff amounts but were sensitive to runoff timing relative to washoff.

Arachis↗
PubMed2006

New peanut (Arachis hypogaea) phytoalexin with prenylated benzenoid and but-2-enolide moieties.

A new pigmented, optically active, low molecular weight metabolite has been isolated from peanut (Arachis hypogaea) kernels challenged by four species of Aspergillus. The structure of the new compound, termed SB-1, was elucidated by analysis of 1H NMR, 13C NMR, and mass spectrometric data. The SB-1 molecule bears prenylated benzenoid and but-2-enolide moieties and represents an unusual class of compounds. The closest known analogue to SB-1 was isolated from heartwood of Pericopsis elata. Both A. hypogaea and P. elata belong to the family Leguminosae. The new metabolite was accumulated in different peanut genotypes challenged by five Aspergillus species and may be an important representative of a new class of peanut phytoalexins. SB-1 production often exceeds production of major known stilbenes.

4-Butyrolactone↗
PubMed1999

Pesticide inactivation of peanut glutamate dehydrogenase: biochemical basis of the enzyme's isomerization.

Glutamate dehydrogenase (GDH) isomerizes in response to pesticides and environmental chemicals, but the biochemical basis of the isomerization is not known. Clearer understanding of the isomerization would permit expansion of its utility in the diagnosis of the responses of plant tissues to challenged environments. Peanut plants were treated with different rates of Basagran (3-(1-methylethyl)-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide), Bravo 720 (tetrachloroiso-phthalonitrile), and Sevin XLR Plus (1-naphthyl N-methylcarbamate). Free solution isoelectric focusing, followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) fractionated the peanut seed GDH to its constituent subunits and degradation polypeptides. After western transfer to nitrocellulose membrane, the GDH subunits and degradation polypeptides were immunodetected with anti-GDH. The pesticide treatments did not induce increased proteolytic activity, but induced about 50% degradation of the GDH, whereas the GDH of the control peanut suffered only about 25% degradation, thus showing that the degradation rate was about double the rate of de novo synthesis in the pesticide treatments. The heavy displacement of the GDH subunit equilibrium toward degradation explains the biochemical basis of the isomerization reaction.

Arachis↗
PubMed2000

Chemical composition of some wild peanut species (Arachis L.) seeds.

Oil, protein, ash, and carbohydrate contents, iodine value, and fatty acid and sterol compositions were studied in seeds of Arachis trinitensis, A. chiquitana, A. kempff-mercadoi, A. diogoi, A. benensis, A. appressipila, A. valida, A. kretschmeri, A. helodes, A. kuhlmannii, A. williamsii, A. sylvestris, A. matiensis, A. pintoi, A. hoehnei, A. villosa, and A. stenosperma. Oil content was greatest in A.stenosperma (mean value = 51.8%). The protein level was higher in A. sylvestris (30.1%) and A. villosa (29.5%). Mean value of oleic acid varied between 30.6% (A. matiensis) and 46.8% (Arachis villosa), and linoleic acid oscillated between 34.1% (A. villosa) and 47.4% (A. appressipila). The better oleic-to-linoleic (O/L) ratio was exhibited by A. villosa (1.38). Some species showed higher concentration of behenic acid. The greatest level of this fatty acid was found in A. matiensis (6.2%). Iodine value was lower in A. valida (99.2). The sterol composition in the different peanut species showed higher concentration of beta-sitosterol (mean values oscillated between 55.7 and 60.2%) followed by campesterol (12.4-16. 5%), stigmasterol (9.7-13.3%), and Delta(5)-avenasterol (9.7-13.4%). The chemical quality and stability of oils (iodine value and O/L ratio) from wild peanut studied in this work are not better than those of cultivated peanut.

Arachis↗
PubMed2005

Structures and electronic properties of peanut-shaped dimers and carbon nanotubes.

The structures and electronic properties of peanut-shaped dimers and carbon nanotubes constructed from C60 molecules are investigated using ab initio self-consistent field molecular and crystal orbital methods based on the density-functional theory. The calculations show that the formation of peanut-shaped structures without octagonal carbon rings is energetically favorable. The obtained band structures indicate that the peanut-shaped nanotube can be a semiconductor or a metal.

Journal Article↗
PubMed1982

The surface glycoproteins of human skin fibroblasts detected after electrophoresis by the binding of peanut (Arachis hypogaea) agglutinin and Ricinus communis (castor-bean) agglutinin I.

A new methodology was developed to study the cell-surface glycoproteins of cultured human skin fibroblasts. This was based on the binding of a variety of biotinyl-lectins to nitrocellulose electrophoretic transfers of total fibroblast lysates after separation in sodium dodecyl sulphate/polyacrylamide gels, followed by reaction with avidin-biotinyl-peroxidase complexes and detection with 3,3'-diaminobenzidine. The technique proved to be very sensitive and a large number of glycoproteins were detected by binding of concanavalin A and wheat-germ agglutinin. Binding of peanut agglutinin and to a lesser extent of Ricinus communis agglutinin I were found to be dependent on prior removal of sialic acid residues from the glycoproteins. Since by treatment of intact viable cells with neuraminidase only external sialic acid residues were removed, peanut agglutinin and Ricinus communis agglutinin I could thus be utilized for selective detection of cell-surface glycoproteins. Also, because peanut agglutinin was known to bind preferentially to oligosaccharides of the O-glycosidic type, and Ricinus communis agglutinin I to those of the N-glycosidic type, the two lectins were complementary in displaying the surface glycoproteins and in providing information about their oligosaccharide composition.

Arachis↗
PubMed1994

Analysis of the optical absorption and magnetic-circular-dichroism spectra of peanut peroxidase: electronic structure of a peroxidase with biochemical properties similar to those of horseradish peroxidase.

The electronic structures of the cationic isoenzyme of peanut peroxidase, horseradish peroxidase (isoenzyme C) and bovine liver catalase are compared through analysis of their optical absorption and magnetic c.d. (m.c.d.) spectral properties. The spectral data for the native resting states and compounds I and II of peanut peroxidase (PeP) are reported. The absorption and m.c.d. data for the native PeP exhibit bands characteristic of the high-spin ferric haem. The absorption spectrum of PeP compound I closely resembles that observed for the HRP compound I species. The m.c.d. data for PeP I clearly identifies that ring oxidation has occurred. One-electron reduction forms the PeP compound II species. The absorption and m.c.d. spectra recorded for PeP II exhibit the well-resolved spectral characteristics previously observed for both HRP compound II and catalase compound II. The spectral data of PeP with HRP and catalase are compared. The data clearly indicate that the m.c.d. spectral patterns of both plant peroxidases (PeP and HRP) are very similar and, therefore, the electronic structures of their resting states, and as well their primary and secondary compounds, must be similar. The m.c.d. data suggest that, while the compound I species of PeP and HRP belong to one electronic class, catalase compound I belongs to a different class. These data emphasize how the ground states of these two classes of oxidized haem, may be characterized as predominantly 2A2u (PeP I and HRP I) or 2A1u (catalase I). Peanut peroxidase is the second plant peroxidase for which the electronic structure of the compound I intermediate has been studied using the m.c.d. technique. The similarities with horseradish peroxidase allow us to suggest that plant peroxidases may operate by the same general mechanism, in spite of the low degree of sequence similarity between their polypeptide chains.

Animals↗
PubMed1980

Expression of peanut agglutinin receptors on virus-induced preleukemic cells in mice.

Preleukemic bone marrow and spleen cells of irradiated C57BL/6 mice that were inoculated with the radiation-induced leukemia virus variant D-RadLV differ from autonomous end-stage leukemia cells in the expression of the receptor for peanut agglutinin. As a result, the preleukemic cells are agglutinated by peanut agglutinin and the end-stage cells are not. This observation provides further evidence that preleukemic cells possess surface markers similar to those of the prothymocyte. In vitro and in vivo thymocyte-virus interactions reveal that cells susceptible to D-RadLV transformation are present mainly among the peanut agglutinin-receptor-bearing thymocyte population which has previously been demonstrated to be immunologically immature.

Animals↗
PubMed1990

Molecular cloning of complementary DNAs encoding two cationic peroxidases from cultivated peanut cells.

We have isolated, cloned, and characterized two cDNAs corresponding to the mRNAs for cationic peroxidases synthesized by cultured peanut cells. The first clone was obtained from a phage lambda gt11 library screened with antibodies directed against the major secreted isozyme. Its predicted amino acid sequence, deduced from the 1228-base-pair (bp) cDNA, revealed a 22-amino acid signal peptide and a 294-amino acid mature protein (Mr, 31,228). The second clone was isolated from a lambda gt10 library screened with oligonucleotides corresponding to the regions for acid/base catalysis and the fifth ligand of heme. This cDNA (1344 bp) encodes a protein (330 amino acids) with a mature peptide of 307 residues (Mr, 32,954). The two peanut peroxidases are 46% homologous. The estimated gene copy numbers of these peroxidases might be close to 1 or 2 per haploid genome. A comparison of the amino acid sequence of these peanut peroxidases with other known isozymes shows two already known regions of homology (the region for acid/base catalysis and the fifth ligand of heme). Moreover, some new characteristics appeared such as a glycosylation site identical in five of the seven isozymes, a putative antigenic determinant common to all the isozymes, and a region of the highest homology. A secondary structure prediction showed that it corresponds to a 16-amino acid helix linked to the next one by a long stretch of beta strands and coils and might represent a critical structural element.

Amino Acid Sequence↗
PubMed2004

Introduction of food during the infant's first year: a study with emphasis on introduction of gluten and of egg, fish and peanut in allergy-risk families.

AIM: The aim of the current study was to retrospectively examine introduction of food during the first year in a representative sample of Swedish children. A secondary aim was to study how parents with history of atopy introduced food to their infants. METHODS: Data derive from 467 infants who visited child health centres in three different counties in Sweden for health check-up at 12 mo of age. The parents were asked to fill in a questionnaire about breastfeeding and/or formula feeding, time of introduction of weaning food focusing on cow's milk, follow-on formula, porridge, fish and egg. Questions regarding hypersensitivity in the family, peanut consumption of mother as well as in the child, and questions about number of siblings, ethnic background and parental education were included. RESULTS: Compliance with suggested introduction of gluten-containing food was low; as many as 45% had avoided gluten until 6 mo of age, instead of introducing gluten between 4 and 6 mo. Only 33% of parents with stated family hypersensitivity avoided giving their child fish and 23% avoided egg during the first year, even though this recommendation was present at the time of the study. Almost 50% of all mothers had avoided peanuts during pregnancy even though there was no such advice. The avoidance of peanut was not connected to hypersensitivity in the family. CONCLUSION: These results suggest that time of introduction of gluten was not in accordance with the current recommendation. The results imply that there is a need to follow up if and how this feeding information is distributed to parents with infants and also to sharpen the information to the right target groups, otherwise implementation of preventive strategies will be less useful.

Age Factors↗