Laccase-mediated enhancement of the properties of regenerated fibers from wheat gliadin

In this study, laccase-mediated crosslinking was used to develop regenerated protein fibers from wheat gliadin with good mechanical properties and water stability. The oxygen consumption during laccase catalyzed oxidation of gliadin, molecular weight of gliadin, mechanical properties, water stability, thermal properties and morphology of gliadin fibers were tested to prove the effect of laccase as the crosslinker of gliadin. The rapid decrease of dissolved oxygen in gliadin solution indicated laccase was active in oxidizing gliadin. The results of SDS-PAGE and SEC demonstrated that laccase-mediated crosslinking reaction effectively occurred. The mechanical properties and water stability of the gliadin fibers with laccase treatment significantly were improved. The fibers from gliadin with laccase treatment exhibited a much smoother and more uniform surface was observed by SEM for the laccase-mediated modified gliadin fibers.     

Fractionation of tryptic gliadin hydrolysates based on proline levels

The central domain (CD) and terminal domains (TDs) of wheat gliadins contain high and low levels of the amino acid proline (Pro), respectively. The CD is rather hydrophilic while the TDs are rather hydrophobic and contain most of the ionisable amino acids, although present only in low levels. Therefore, peptides derived from the CD or TDs may strongly differ in their physico–chemical properties. Trypsin cleaves peptide bonds at lysine and arginine residues which are mainly present in the TDs and was used in the present study. Several fractionation methods were examined to isolate CD and TD related peptides from tryptic hydrolysates. Pro was used as a marker for CD and TD related peptides. Both semi-preparative reversed-phase HPLC separation and fractionation of the water-soluble peptides of the tryptic gliadin hydrolysates by graded ethanol precipitation resulted in peptide fractions with different Pro levels. Whereas the fractions precipitating up to 90% ethanol were Pro rich, a Pro poor fraction consisting of small peptides was soluble in 90% ethanol solution. The water insoluble peptides of the tryptic hydrolysates also showed a low Pro level. Ultrafiltration of the water-soluble peptides using a 5-k membrane resulted in small Pro poor peptides and larger Pro rich peptides.     

Towards a new gliadin reference material–isolation and characterisation

Twenty-eight wheat cultivars representative of the three main European wheat producing countries, France, UK and Germany, were selected as a source for the preparation of a reference gliadin. One kilogram of kernels from each cultivar were mixed and milled. The resulting white flour was defatted and vacuum dried. Albumins and globulins were eliminated by extraction using 0.4 M NaCl solution and gliadins were extracted with 60% ethanol. The gliadin extracts were concentrated, desalted by ultrafiltration, freeze-dried, and homogenised. After tests had shown good solubility and homogeneity, aliquots of the reference gliadin were sent to 16 different laboratories for further investigations: The material was analysed by various methods including RP-HPLC, SE-HPLC, RP-HPLC-ESI-MS, MALDI-TOF, capillary electrophoresis, acid-PAGE, 2D-PAGE, SDS-PAGE and immunoblotting and ELISA-tests with different monoclonal and polyclonal antibodies. The results showed that the gliadin composition of the source flour and the reference gliadin matched perfectly, demonstrating that no major gliadin components had been lost during the isolation procedure. The reference gliadin showed good immunochemical sensitivity with different gliadin antibodies in enzyme immunoassays. Because of its high protein and gliadin content, good solubility, homogeneity, stability and representative character, the product is regarded as a suitable universal reference material.     

Fabrication and characterization of wheat gliadin hydrogels with high strength and toughness

Fabricating a hydrogel with high strength and toughness is still a challenge in many fields. Here, we prepared gliadin-based hydrogels by chemical cross-linking gliadin in acetic acid solution (GS) with glutaraldehyde (GA). Subsequently, the overall properties of the fabricated hydrogels were systematically investigated in terms of their mechanical properties, swelling ratio, weight loss, thermal stability, and the chemical/physical interactions in hydrogels. Results showed that the gliadin-based chemically cross-linked hydrogels exhibited excellent mechanical properties. The optimized hydrogel exhibited the compressive stress of 1.8 MPa at a strain of 70%, and an excellent self-recovery property after 30 cycles of loading-unloading treatments. The strength and toughness of the hydrogels could be tailored by adjusting the ratio of GS/GA. The chemical cross-linking (aldehyde-ammonia reaction) was the main molecular interaction in the hydrogels, including single-/multi-site crosslinking, and the hydrogen bond was the only physical cross-linking in the hydrogels. Moreover, the swelling ratio of the fabricated hydrogels performed a concentration negative-dependency in GA or GS concentration. And a higher GS concentration (40%) with an appropriate GA content (3.0%) could resist the degradation of hydrogels. In addition, the thermodynamic properties of hydrogels also improved by the GA addition. Overall, these findings suggested that gliadin can be applied for fabricating hydrogels with tunable mechanical properties, which will unlock the high-utilization of gliadin as biopolymer and biocompatible materials.     

β-Elimination reactions and formation of covalent cross-links in gliadin during heating at alkaline pH

The aim of this study was to increase insight into gluten polymerisation. While previous research on this topic focused on disulfide (SS) bonds, the present paper focuses on cross-links based on dehydro-protein formation through β-elimination reactions. Gliadin, the monomeric fraction of gluten containing no free sulfhydryl (SH) groups, was heated for 120 min at pH 8.0 and 130 °C, and cross-link formation was evaluated by determining extractability in sodium dodecyl sulfate containing buffer, reaction products of β-elimination reactions, and cross-links involving the latter. Heating decreased gliadin extractability. Reduction of SS bonds increased extractability of heated gliadin, but did not restore it to that of non-heated gliadin, suggesting contribution of both SS and non-SS bonds to gliadin cross-linking. Decreased SS levels and the presence of dehydroalanine and SH groups in heated gliadin samples indicated cleavage of SS bonds by β-elimination reactions. Some of the formed free SH groups were then involved in oxidation and/or SH–SS interchange reactions leading to intermolecular SS bonds. In addition, amino acid analysis revealed formation of an irreversible non-SS cross-link between dehydroalanine and the free SH group of cysteine, namely lanthionine. In conclusion, non-SS bonds may well contribute to the gluten network under specified reaction conditions.     

Reactivity of gluten detecting monoclonal antibodies to a gliadin reference material

People affected by coeliac disease need to adhere to a life-long gluten-free diet to avoid symptoms. ELISA-tests are seen as the mainstay for the detection of gluten in gluten-free food because of their sensitivity. They can, however, yield different gluten amounts depending on the antibody and reference material used. We compared the reactivity of three prominent mouse anti-gliadin-antibodies to a reference gliadin isolated from 28 common bred European wheat varieties. The reference material proteins were labelled with fluorescent dye Cy3. They were then separated by 2DE and transferred by Western blot onto low fluorescent PVDF-membranes, followed by incubation with the three primary anti-gliadin antibodies one by one. Detection of the reacting proteins used anti-mouse antibody which was labelled with fluorescent dye Cy5. The use of this technique made it possible to co-detect the 2DE-image of the reference material proteins (Cy3) and proteins reacting with the respective antibody (Cy5). The three investigated antibodies had dissimilar reactivities with different proteins of the reference gliadin. Antibodies R5 and PN3 reacted mainly with gliadin fractions, antibody 401.21 mainly with high molecular weight glutenins. The results confirm the individual specificity of these antibodies and demonstrate the importance of validating immunochemical methods for gluten detection.     

Using the Gluten Peak Tester as a tool to measure physical properties of gluten

The functional properties of wheat are largely dictated by composition and interactions of the gluten proteins. All flours contain gliadin and glutenin, but produce baked products of varying quality, which provides evidence that gluten proteins from different wheats possess different properties. A common method to study differences in gluten properties, which is utilized in this study, is fractionation/reconstitution experiments to understand how various gliadin to glutenin ratios and how fractions from different wheat sources affect gluten aggregation properties. Gliadin and glutenin from a vital wheat gluten were fractionated with 70% ethanol and reconstituted at various gliadin to glutenin ratios. Gliadin and glutenin from a Canadian eastern soft, eastern hard and western hard wheat (14% moisture) were fractionated and substituted between flours at the native gliadin to glutenin ratio. Gluten combinations were evaluated with a Gluten Peak Tester at constant temperature and mixing. Varying gliadin to glutenin ratio showed that 50:50 is optimal for fast gluten aggregation while amount of glutenin dictates strength. Substitution experiments showed that replacing good quality gluten fractions with those from a lower quality wheat decreases gluten quality, and vice versa. Data also showed that cultivar specific differences in gliadin and glutenin are more important in dictating gluten strength (torque), while gliadin to glutenin ratio dictates aggregation time (PMT) independent of the source of fractions. The study demonstrated the ability of the improved method to evaluate gluten aggregation by controlling for all variables except the one being tested. The data also revealed information about gluten aggregation properties never before seen.     

Mechanical properties of flax-g-poly(methyl acrylate) reinforced phenolic composites

In order to develop composites with better mechanical properties and environmental performance, it becomes necessary to increase the hydrophobicity of the natural fibers and to improve the interface between matrix and natural fibers. Graft copolymerization of natural fibers is one of the best methods to attain these improvements. Only few workers have reported the use of graft copolymers as reinforcing material in the preparation of composites. So in the present paper, we report the preparation of graft copolymers of flax fibers with methyl acrylate (MA) using Fenton’s reagent (FAS-H₂O₂) as redox system. Synthesized flax-g-poly(MA) was characterized with FTIR, TGA/DTA, scanning electron microscopy (SEM), and X-ray diffraction (XRD) techniques. Composites were prepared using flax-g-poly(MA) as a reinforcement and phenolformaldehyde (PF) as the binding material. Mechanical properties of phenol-formaldehyde composites were compared and it has been found that composites reinforced with flax-g-poly(MA) showed improvement in mechanical properties. Composites reinforced with flax-g-poly(MA) showed better tensile strength (235 N) and compressive strength (814 N) in comparison to composites reinforced with original flax fiber which showed lesser tensile strength (162 N) and compressive strength (372 N). Composites reinforced with flax-g-poly(MA) shows the improved MOR, MOE, and SP.     

离子束介导大豆DNA转入普通小麦后代的麦谷蛋白和醇溶蛋白分析

为了研究离子束介导大豆DNA转入普通小麦的效果,应用SDS-PAGE和A-PAGE电泳分析了离子注入介导大豆DNA转入普通小麦后代中高蛋白含量植株的麦谷蛋白和醇溶蛋白。SDS-PAGE电泳结果表明,与对照相比有8个高蛋白含量植株的HMW-GS谱带数目发生了变化或着色增强。A-PAGE电泳结果表明,与对照相比有9个高蛋白含量植株的醇溶蛋白谱带数目及着色强度发生了变化。说明离子束介导大豆DNA转入普通小麦后代中的高蛋白含量植株在醇溶蛋白和麦谷蛋白基因位点上可能出现了变异。     

Production and optimization of indole acetic acid by indigenous micro flora using agro waste as substrate

Indole Acetic Acid (IAA) producing bacterium was isolated from the Rhizosphere soil and identified as Rhizobium sp. and Bacillus sp., Optimization of Indole acetic acid production was carried out at different cultural conditions, such as pH, temperature and substrate with Rhizobium sp., Bacillus sp. and Rhizobium sp., produced higher amount of Indole acetic acid (6.1 mg mL(-1)) than the Bacillus sp., (4.4 mg mL(-1)) at pH 7 and 37 degrees C in the Bengal gram substrate. Partial purification of Indole acetic acid was done by Thin Layer Chromatography (TLC). In conclusion Rhizobium sp., appear to be a suitable soil microorganism for high level of IAA production.     

用SPSS建立岳阳名优黄茶的产量预测模型

利用湖南省汨罗市2003~2014年期间上年12月上旬至下年5月下旬的逐日气象观测资料及岳阳县黄沙街茶叶示范场2004~2014年名优茶产量资料,在计算上运用界面友好的SPSS软件,采用逐步回归方法,对名优黄茶产量与气象条件之间的关系进行分析研究。结果表明:名优茶产量与气象条件之间有着密切的关系,与2月平均风速、1月上旬平均相对湿度、1月中旬平均最高气温等3个气候因子显著相关,逐步回归后建立的春茶产量预测的数学模型,平均预报精确度达到95%,检验效果良好。     

Properties of polymers as a nanoscale material for fibers in leather

Hyperbranched polymers, an innovative class of nano-polymers, could enhance the properties of fibers owning to their unique structures. In this study, the ester compound (HPAE) of 3-(bis(2-hydroxyethyl)amino)propionic acid and pentaerythritol was treated with undecylenic acid to obtain novel hyperbranched multiterminal alkenyl polymers (HPAE-UAs). The sizes of the HPAE-UAs could be controlled conveniently from 400 to 1300 nm by adjusting the capped fraction of the hydroxyl groups with undecylenic acids. The molecular structures of HPAE-UAs were characterized by means of FT-IR and ¹H-NMR. Then, the effect of the HPAE-UAs on the structures, thermal, and mechanical properties of the wet blue leather were investigated. TEM and SEM demonstrated that the spacing between fibers was enlarged. The thermogravimetric analysis showed that the residual volume of leather could reach up to 30.3 % at about 500 °C. Furthermore, the shrinkage temperature increased to 89.4 °C. It was found that the HPAE-UAs used in leather could improve the thermal performance, physical and mechanical properties. All of these results indicate that HPAE-UAs can be used as a fatliquor with retanning in leather process.     

Production of min-seed tubers using a modular system of plant micropropagation

Summary An efficient and low cost modular system for the production of mini-tubers as a source for conventional seed tubers is reported. In this system, microplants are soil grown and produce minitubers of 5 to 25 mm diameter. The system is based on the use of pre-sterilized disposable plastic containers which allow micropropagation, weaning, hardening, and soil growing of micropropagated plants in the same container. Depending upon the cultivar, the modular system allows production of 2900 to 6600 mini-tubers/m² in a glasshouse.     

Rapid degradation of gliadin peptides toxic for coeliac disease patients by proteases from germinating cereals

We report the isolation and characterisation of proteases from germinated wheat, rye and barley, and their ability to degrade gliadin peptides toxic for coeliac patients. It is shown for the first time that these proteases cleave these peptides rapidly into non-toxic fragments with less than nine amino acids. These proteases have distinct advantages when compared to bacterial or fungal proteases, and are promising candidates for the detoxification of gluten containing foods and for oral therapy for celiac patients.     

UV-induced coloration of cotton fabrics by photografting of acrylamido dyes using acrylamide as a comonomer

Formulations of acrylamido dyes containing comonomers can be photografted onto cotton fabric upon UV irradiation at room temperature without neutral salts, which makes it a novel coloration process of excellent environmental friendliness. The photografting of the dyes can be assisted by the copolymerization of the acrylamide comonomer which may reduce the steric hindrance of the bulky dyes. About 90 % of the dyes and 94 % of the acrylamide are photopolymerized in the solution and the degree of polymerization is estimated to be 13.2 according to ¹H-NMR and MALDI-TOF mass analyses. The optimal K/S values of the grafted cotton fabrics showed 13.3 and 12.3 for red and yellow dyes, respectively. The optimal UV-grafting coloration can be achieved when a UV energy of 25 J/cm² was irradiated on the padded fabrics with a formulation of 0.65 mole ratio of acrylamide to the dyes, 7 wt% acetophenone photoinitiator (Irgacure 2959) based on the dye weight under pH 6. Furthermore, the color fastness properties of the grafted fabric were superior to those of conventional reactive dyeing of the dyes due to higher molecular weight of the polymerized dyes.     

Field performance of potato microtubers as propagation material

Summary In five field trials with the cultivars Gloria (early), Bintje (mid-early) Désirée (mid-late) and Morene (late), crops grown from conventional 28–35 or 35–45 mm seed were compared with crops grown from microtubers, of various sizes and from various sources, that had been producedin vitro. The following means to quicken initial crop development from the micropropagated material were tested: large microtubers, plastic soil cover, and transplanting of plantlets grown from microtubers pre-planted in a glasshouse. Crops grown from microtubers weighing less than half a gram yielded much less than crops grown from conventional seed crops but their yields were increased by each treatment. With the later-maturing cultivars, which generally produce few tubers per plant, the yields within seed grades from plants grown from transplanted microtuber plants were comparable with those of conventional crops. Reasons are given, why direct planting of microtubers, with or without plastic foil, is not a practical option.     

Surface properties and locations of gluten proteins and lipids revealed using confocal scanning laser microscopy in bread dough

Surface properties of gluten proteins were measured in a dilation test and in compression and expansion tests. The results showed that monomeric gliadin was highly surface active, but polymer glutenin had almost no surface activity. The locations of those proteins in bread dough were investigated using confocal scanning laser microscopy and compared with polar and nonpolar lipids. Added gluten proteins participated in the formation of the film or the matrix, surrounding and separating individual gas cells in bread dough. Gliadin was found in the bulk of dough and gas ‘cell walls’. Glutenin was found only in the bulk dough. Polar lipids were present in the protein matrix and in gas ‘cell walls’, as well as at the surface of some particles, which appeared to be starch granules. However, nonpolar lipid mainly occurred on the surface of particles, which may be starch granules and small lipid droplets. It is suggested that the locations of gluten proteins in bread dough depends on their surface properties. Polar lipid participates the formation of gluten protein matrix and gas ‘cell walls’. Nonpolar lipids may have an effect on the rheological properties by associating with starch granule surfaces and may form lipid droplets.     

Comparison of the conformational and nutritional changes of deamidated wheat gliadin by citric acid and hydrochloric acid

Deamidated wheat gliadins were prepared using hydrochloric acid (HCl) and citric acid (HDWG and CADWG), respectively. Their secondary structure, protein molecular interaction, thermal properties and nutritional changes were compared by Fourier transform infrared spectroscopy (FTIR), Raman spectrum, atomic force microscopy (AFM), differential scanning calorimetry (DSC), and amino acid analysis, respectively. Secondary structures and molecular vibration model showed slight difference between HDWG and CADWG, but significant difference between control gliadin and deamidated wheat gliadins. HDWG and CADWG had different shapes on the mica surface that the former showed some extent of linear aggregates and fibrils while the latter mainly exhibited globular aggregates. This result was further supported by thermal characteristics that CADWG had higher denaturation temperature than control gliadin and HDWG. Citric acid deamidation could increase the Lysine content and better maintain the total essential amino acids of in vitro digests of gliadin compared with HCl.     

Production of the neurotoxin BMAA by a marine cyanobacterium

Diverse species of cyanobacteria have recently been discovered to produce the neurotoxic non-protein amino acid β-methylamino-L-alanine (BMAA). In Guam, BMAA has been studied as a possible environmental toxin in the diets of indigenous Chamorro people known to have high levels of Amyotrophic Lateral Sclerosis/ Parkinsonism Dementia Complex (ALS/PDC). BMAA has been found to accumulate in brain tissues of patients with progressive neurodegenerative illness in North America. In Guam, BMAA was found to be produced by endosymbiotic cyanobacteria of the genus Nostoc which live in specialized cycad roots. We here report detection of BMAA in laboratory cultures of a free-living marine species of Nostoc. We successfully detected BMAA in this marine species of Nostoc with five different methods: HPLC-FD, UPLC-UV, Amino Acid Analyzer, LC/MS, and Triple Quadrupole LC/MS/MS. This consensus of five different analytical methods unequivocally demonstrates the presence of BMAA in this marine cyanobacterium. Since protein-associated BMAA can accumulate in increasing levels within food chains, it is possible that biomagnification of BMAA could occur in marine ecosystems similar to the biomagnification of BMAA in terrestrial ecosystems. Production of BMAA by marine cyanobacteria may represent another route of human exposure to BMAA. Since BMAA at low concentrations causes the death of motor neurons, low levels of BMAA exposure may trigger motor neuron disease in genetically vulnerable individuals.