Substrate Preference of γ-Glutamyltransferase from Caps of Fruiting Bodies of Lentinus edodes

Three kinds of proteins (BA-1, BA-2 and BA-3) allergenic to the IgE antibody of allergenic individuals were isolated from buckwheat seeds. These three proteins were essentially homogeneous as judged by both polyacrylamide gel electrophoresis and SDS-polyacrylamide gel electrophoresis. The amino acid composition of BA-1 and BA-2 was very similar, and the molecular weight of each allergenic protein was between 8000–9000 by SDS-polyacrylamide gel electrophoresis. One of them was a trypsin inhibitor, and their immunoreactivity was quite stable to heating at 100°C for 60 min.     

Identification and partial characterization of the allergenic proteins of Ricinus communis L. pollen - a new approach

The pollen of Ricinus communis L., a potentially allergenic plant, was extracted to identify the allergenic determinants responsible for causing respiratory disorders. The soluble proteins were extracted and subjected to ammonium sulphate precipitation at 80% saturation and the total protein separated on 12% SDS-Polyacrylamide gel. In order to avoid the time consuming and expensive biochemical methods of column chromatography, each band was directly recovered from the gel by electroelution and the allergenic proteins identified directly by skin tests, without the necessity of Phadezym RAST or ELISA inhibition by reaction with serum IgE, the general procedure to identify the allergens. The fourth and the fifth band in the protein profile of R. communis pollen, RC4 (77 kD) and RC5 (66 kD) were the two major allergenic components. RC3 (91 kD) also induced a considerable amount of reactivity in sensitive patients. Contrary to the earlier reports of protein bands of R. communis ranging from 14 kD to 70 kD, 4 bands above 70 kD i.e. RC1 (123 kD), RC2 (97 kD), RC3 (91 kD) and RC4 (77 kD) are reported here for the first time. Immunodiffusion analysis with pooled sera of patients sensitive to the total extract also revealed similar results.     

Evidence of a novel allergenic protein Narcin in the bulbs of Narcissus tazetta

Several plant-derived allergens have been identified which result in the formation of immunoglobulin E antibodies. Primarily, these allergens belong to the protein families including seed storage proteins, structural proteins and pathogenesis-related proteins. Several allergens are also reported from flower bulbs which cause contact dermatitis. Such symptoms are highly common with the bulb growers handling different species of Narcissus. Narcissus toxicity is also reported if the bulbs are consumed accidentally. The present study aimed to characterize the protein from the bulbs of Narcissus tazetta responsible for its allergenic response. A 13 kDa novel allergenic protein, Narcin was isolated from the bulbs of Narcissus tazetta. The protein was extracted using ammonium sulfate fractionation. The protein was further purified by anion exchange chromatography followed by gel filtration chromatography. The N-terminal sequence of the first 15 amino-acid residues was determined using Edman degradation. The allergenicity of the protein was measured by cytokine production using flow cytometry in peripheral blood mononuclear cells. Further estimation of total IgE was performed by ELISA method. This novel protein was found to induce pro-inflammatory cytokines and thus induce allergy by elevating total IgE level. The novel protein, Narcin isolated from Narcissus tazetta was found to exhibit allergenic properties.     

Cod and soy proteins compared with casein improve glucose tolerance and insulin sensitivity in rats

The aim of the present study was to determine the effects of feeding various dietary proteins on insulin sensitivity and glucose tolerance in rats. Male Wistar rats were fed for 28 days with isoenergetic diets containing either casein, soy protein, or cod protein. Cod protein-fed and soy protein-fed rats had lower fasting plasma glucose and insulin concentrations compared with casein-fed animals. After intravenous glucose bolus, cod protein- and soy protein-fed rats induced lower incremental areas under glucose curves compared with casein-fed animals. Improved peripheral insulin sensitivity was confirmed by higher glucose disposal rates in cod protein- and soy protein-fed rats (15.2 +/- 0.3 and 13.9 +/- 0.6 mg. kg(-1). min(-1), respectively) compared with casein-fed animals (6.5 +/- 0.7 mg. kg(-1). min(-1), P < 0.05). Moreover, test meal experiments revealed that, in the postprandial state, the lower plasma insulin concentrations in cod protein- and soy protein-fed animals could be also due to decreased pancreatic insulin release and increased hepatic insulin removal. In conclusion, the metabolic responses to three common dietary proteins indicate that cod and soy proteins, when compared with casein, improve fasting glucose tolerance and peripheral insulin sensitivity in rats.     

Airborne Poaceae pollen in Porto (Portugal) and allergenic profiles of several grass pollen types

This work aims to investigate the presence of airborne grass pollen and to identify antigenic and allergenic profiles from eight different grass species collected in the Porto region (Portugal). Poaceae airborne pollen, sampled using a Hirst-type volumetric trap during 2003–2007, was the second most abundant type, and high concentrations were found from April to August. Pollen proteins extracted from the eight grass species collected were separated by SDS-PAGE, being the allergenic profile investigated by immunoblotting using sera from atopic patients and maize profilin polyclonal antibody (ZmPRO3). Pollen extract profiles showed several bands ranging from 10 to 97 kDa. In immunoblotting studies, a low molecular weight protein (12–13 kDa) was recognized by profilin antibody. Also, in all pollen extracts except Zea mays, the IgE binding proteins of 12–13 kDa were detected in sera from the 25 patients with different sensitization profiles presenting high IgE values (>80 kU/l). This protein can be considered as a potential causal agent of the allergic respiratory diseases.     

Disruption of allergenic activity of the major grass pollen allergen Phl p 2 by reassembly as a mosaic protein

The recognition of conformational epitopes on respiratory allergens by IgE Abs is a key event in allergic inflammation. We report a molecular strategy for the conversion of allergens into vaccines with reduced allergenic activity, which is based on the reassembly of non-IgE-reactive fragments in the form of mosaic proteins. This evolution process is exemplified for timothy grass pollen-derived Phl p 2, a major allergen for more than 200 million allergic patients. In a first step, the allergen was disrupted into peptide fragments lacking IgE reactivity. cDNAs coding for these peptides were reassembled in altered order and expressed as a recombinant mosaic molecule. The mosaic molecule had lost the three-dimensional structure, the IgE reactivity, and allergenic activity of the wild-type allergen, but it induced high levels of allergen-specific IgG Abs upon immunization. These IgG Abs crossreacted with group 2 allergens from other grass species and inhibited allergic patients' IgE binding to the wild-type allergen. The mosaic strategy is a general strategy for the reduction of allergenic activity of protein allergens and can be used to convert harmful allergens into safe vaccines.     

Isoform identification, recombinant production and characterization of the allergen lipid transfer protein 1 from pear (Pyr c 3)

Non-specific lipid transfer proteins belonging to LTP1 family represent the most important allergens for non pollen-related allergies to Rosaceae fruits in the Mediterranean area. Peach LTP1 (Pru p 3) is a major allergen and is considered the prototypic allergenic LTP. On the contrary, pear allergy without pollinosis seems to be under-reported when compared to other Rosaceae fruits suggesting that the as-yet-uncharacterized pear LTP1 (Pyr c 3) has in vivo a low allergenicity. We report here on the identification of four cDNAs encoding for LTP1 in pear fruits. The two isoforms exhibiting amino acid sequences most similar to those of peach and apple homologues were obtained as recombinant proteins. Such isoforms exhibited CD spectra and lipid binding ability typical of LTP1 family. Moreover, pear LTP1 mRNA was mainly found in the peel, as previously shown for other Rosaceae fruits. By means of IgE ELISA assays a considerable immunoreactivity of these proteins to LTP-sensitive patient sera was detected, even though allergic reactions after ingestion of pear were not reported in the clinical history of the patients. Finally, the abundance of LTP1 in protein extracts from pear peel, in which LTP1 from Rosaceae fruits is mainly confined, was estimated to be much lower as compared to peach peel. Our data suggest that the two isoforms of pear LTP1 characterized in this study possess biochemical features and IgE-binding ability similar to allergenic LTPs. Their low concentrations in pear might be the cause of the low frequency of LTP-mediated pear allergy.     

COMPARATIVE STUDIES OF HIGHLY BASIC PROTEINS OF OX BRAIN AND RAT BRAIN. MICROHETEROGENEITY OF BASIC ENCEPHALITOGENIC (MYELIN) PROTEIN

(1) The total amount of highly basic proteins in acid extracts of whole ox brain, ox white matter and ox grey matter was determined quantitatively after electrophoresis on 5% polyacrylamide gels at pH 10-6 in the presence of 8 M-urea. (2) Ox white matter gave 13 mg and ox grey matter 2 mg of highly basic proteins per g fresh tissue on treatment with 0-03 n -HCl. The yield of total basic proteins of ox white matter increased to 17-6 mg/g fresh brain on stepwise extraction at pH 3-0, 2-0 and 1-0; the extract at pH 3.0 accounted for 90 per cent of the total basic proteins. (3) The high encephalitogenic activity of the fraction of highly basic proteins extracted at pH 3.0 from ox white matter indicated that these basic proteins were derived from myelin. It is suggested that the amount of basic proteins in a sample of brain extracted under these conditions is proportional to the amount of white matter in the sample. (4) The encephalitogenic (myelin) basic protein fraction was homogeneous with respect to molecular size but could be resolved into at least six components by electrophoresis at high pH. (5) The myelin basic proteins extracted from ox white matter had lower electrophoretic mobilities at high pH than did those of two basic proteins of rat brain apparently derived from myelin.     

Localization of the continuous allergenic sites of ragweed allergen Ra3 by a comprehensive synthetic strategy

A comprehensive synthetic approach, previously introduced by this laboratory for the localization of the full profile of the continuous antigenic sites on proteins, was applied here to localize the continuous sites of ragweed allergen, Ra3, that are recognized by human anti-Ra3 IgE antibodies. The following 10 uniform and overlapping peptides were synthesized and purified: 1-15, 11-25, 21-35, 31-45, 41-55, 51-65, 61-75, 71-85, 81-95 and 91-101. Quantitative radiometric titrations of protein and peptide adsorbents with human IgE, established the full profile of allergenic (IgE binding) sites on Ra3. It was found that Ra3 has four continuous allergenic sites. Antibodies prepared against the IgE binding peptides bound to native Ra3. The findings are briefly discussed in relation to other protein antigenic structures and in terms of design of vaccines using synthetic sites.     

Structure and stability of 2S albumin-type peanut allergens: implications for the severity of peanut allergic reactions

Resistance to proteolytic enzymes and heat is thought to be a prerequisite property of food allergens. Allergens from peanut (Arachis hypogaea) are the most frequent cause of fatal food allergic reactions. The allergenic 2S albumin Ara h 2 and the homologous minor allergen Ara h 6 were studied at the molecular level with regard to allergenic potency of native and protease-treated allergen. A high-resolution solution structure of the protease-resistant core of Ara h 6 was determined by NMR spectroscopy, and homology modelling was applied to generate an Ara h 2 structure. Ara h 2 appeared to be the more potent allergen, even though the two peanut allergens share substantial cross-reactivity. Both allergens contain cores that are highly resistant to proteolytic digestion and to temperatures of up to 100 degrees C. Even though IgE antibody-binding capacity was reduced by protease treatment, the mediator release from a functional equivalent of a mast cell or basophil, the humanized RBL (rat basophilic leukaemia) cell, demonstrated that this reduction in IgE antibody-binding capacity does not necessarily translate into reduced allergenic potency. Native Ara h 2 and Ara h 6 have virtually identical allergenic potency as compared with the allergens that were treated with digestive enzymes. The folds of the allergenic cores are virtually identical with each other and with the fold of the corresponding regions in the undigested proteins. The extreme immunological stability of the core structures of Ara h 2 and Ara h 6 provides an explanation for the persistence of the allergenic potency even after food processing.     

Changes in peptic digestibility of bovine beta-lactoglobulin as a result of food processing studied by capillary electrophoresis and immunochemical methods

Digestion studies constitute a functional tool for allergen characterisation. This strategy for investigating allergenic proteins relates to the observation of increased proteolytic resistance of some proteins recognised to exhibit allergenic potential. beta-Lactoglobulin (betaLG) is one of the major whey proteins, a potent milk allergen and shows a high stability against peptic hydrolysis in its native form. In order to study the impact of milk fermentation process on its digestibility, two complementary analytical methods were applied: capillary zone electrophoresis (CZE) to quantitatively study proteolytic degradation of betaLG isolated from different fermented bovine milk products, and enzyme linked immunosorbent assay (ELISA) to assess differences in immunoreactivity. betaLG, isolated from either raw or pasteurised cow's milk (CM), as expected, showed only minimal digestibility (less than 10% in 2 h). However, when raw milk or pasteurised milk was fermented, the rate of peptic digestion of the protein significantly increased (up to 45% in 2 h). In accordance with changes in digestibility, the immunochemical response for all fermented samples was lower than that of non-fermented references. Raw and pasteurised milk "naturally" fermented in our laboratory only resulted in a slight reduction (betaLG detected is still in the range of milligrams per gram sample), whereas the industrially manufactured sour milk as well as the "Acidophilus milk" reflected a remarkably lower level of immunoreactivity (55-56 microg/g sample).     

Acute amphetamine down-regulates RGS4 mRNA and protein expression in rat forebrain: distinct roles of D1 and D2 dopamine receptors

Administration of psychostimulants modulates mRNA of several regulators of guanine nucleotide-binding protein signaling (RGSs) proteins in the brain. In the present study, the regulation of amphetamine-induced decrease of RGS4 expression in the rat forebrain was evaluated. RGS4 mRNA was reduced by amphetamine in an inverse, dose-dependent manner. The lowest dose (2.5 mg/kg) decreased RGS4 mRNA in caudate putamen for up to 6 h after injection whereas the decrease in several frontal cortical areas was detected at 3 h only. Analysis of RGS4 immunoreactivity by western blotting revealed a decrease 3 h after amphetamine solely in the caudate putamen. Systemic administration of D(1) (SCH23390) or D(2) (eticlopride) receptor antagonists blocked amphetamine-induced locomotion but amphetamine augmented both the SCH23390-induced increase and the eticlopride-induced decrease in RGS4 mRNA in the caudate putamen. Further, the down-regulation of RGS4 immunoreactivity by eticlopride was robust whereas the effect of SCH23390 was blunted as compared with its effect on mRNA. These data suggest that, by decreasing RGS4 expression in the caudate putamen via D(1) receptors, acute amphetamine could disinhibit RGS4-sensitive guanine nucleotide-binding protein alpha-subunit i- and/or q-coupled signaling pathways and favor mechanisms that counterbalance D(1) receptor stimulation.     

Enzymatic preparation of immunomodulating hydrolysates from soy proteins

Soy protein hydrolysates with lower molecular weight were enzymatically prepared by several commercially available proteases (Alcalase 2.4L, Flavourzyme, Trypsin, Papain, Protease A and Peptidase R) with protein recovery varied from 42.59% to 79.87%. Relative content of positively charged peptides was determined on SP Sephadex C-25 using gradient sodium chloride solution as eluents. Immunomodulating properties were evaluated by measuring their effect on in vitro proliferation of murine spleen lymphocytes and phagocytic activity of peritoneal macrophages. The results showed that soy protein hydrolysates (SPHs) prepared with Alcalase and insoluble soy protein (InSP), preferable to other enzymes and soy proteins, have the highest immunomodulating activity and the optimum conditions were determined as follows: E/S=2% (Alcalase), 60 degrees C, pH 8.0, InSP concentration 6% and 225min. Positive correlations were obtained between the immunomodulating activity and content of positively charged peptides. The results suggested that lower molecular weight and positively charged peptides released from soy protein were effective in stimulating immunomodulating activity, thus provided insights into the preparation of potent immunomodulating products.     

Comparison of the aggregation behavior of soy and bovine whey protein hydrolysates

Soy-derived proteins (soy protein isolate, glycinin, and β-conglycinin) and bovine whey-derived proteins (whey protein isolate, -lactalbumin, β-lactoglobulin) were hydrolyzed using subtilisin Carlsberg, chymotrypsin, trypsin, bromelain, and papain. The (in)solubility of the hydrolysates obtained was studied as a function of pH. At neutral pH, all soy-derived protein hydrolysates, particularly those from glycinin, obtained by hydrolysis with subtilisin Carlsberg, chymotrypsin, bromelain, and papain showed a stronger aggregation compared to the non-hydrolyzed ones. This increase in aggregation was not observed upon hydrolysis by trypsin. None of the whey-derived protein hydrolysates exhibited an increase in aggregation at neutral pH. The high abundance of theoretical cleavage sites in the hydrophobic regions of glycinin probably explains the stronger exposure of hydrophobic groups than for the other proteins, which is suggested to be the driving force in the aggregate formation.     

Soy protein recovery in a solvent-free process using continuous liquid-solid circulating fluidized bed ion exchanger

Soy protein concentrates and soy protein isolates act as ingredients in bakery, meat and dairy products, baby formulas, starting materials for spun textured vegetable products, and other nutritional supplements. In this study, the effectiveness of a liquid-solid circulating fluidized bed (LSCFB) ion exchanger is demonstrated for the recovery of soluble soy proteins from full fat and defatted soy flour. Under steady-state operating conditions, about 50% of the proteins could be recovered from the feed streams entering the ion exchanger. The LSCFB was shown to be a promising system for the recovery of soy protein from both defatted and full fat soy flour solutions. As the ion exchange process captures dissolved proteins, the system may offer a less damaging form of processing compared with the acid precipitation process where soy protein aggregates form and functionality is affected. In addition, the LSCFB allows simultaneous adsorption and desorption of the proteins allowing for a continuous operation. No prefiltration of feed containing suspended particles is required as well, because fluidization is used in place of packed bed technology to improve on current ion exchange processes.     

Solubility of soy lipophilic proteins: comparison with other soy protein fractions

Solubility of soy lipophilic proteins (LP) was studied as compared with that of other soy protein fractions. LP, β-conglycinin, glycinin, and soy protein isolate (N-SPI) were prepared under the condition to avoid heat denaturation. Solubility of LP was lower than that of other soy protein fractions under all the tested conditions varying in pH values and ionic strength. The solubility of LP was increased constantly by elevating temperature until 90 °C, whereas that of β-conglycinin and glycinin dropped at high temperature. Temperature-dependent change in solubility of N-SPI might reflect the balance among that of glycinin, β-conglycinin and LP. Based on the results of SDS-PAGE, determination of phospholipid content and Fourier Transform Infrared spectroscopy, we discussed the solubilization behavior of LP relating to its origin and composition.     

Isoelectric precipitation of soybean protein using carbon dioxide as a volatile acid

A novel process is presented for the isoelectric precipitation of soy protein, using carbon dioxide as a volatile acid. By contacting a soy meal extract with pressurized carbon dioxide, the solution pH was decreased to the isoelectric region of the soy proteins. Complete precipitation of the precipitable soy proteins could be achieved for protein concentrations up to 40 g/l at pressures less than 50 bar. Isoelectric precipitation with a volatile acid enabled accurate control of the solution pH by pressure and eliminated the local pH overshoot, usual in conventional precipitation techniques. The advantage of the improved precipitation control was reflected by the morphology of the precipitate particles. Protein aggregates formed by CO₂ were perfectly spherical whereas protein precipitated by sulfuric acid had an irregular morphology. The influence of process variables to control particle size is discussed.     

Effect of Soy Proteins on the Growth of Clostridium perfringens

Proteins that are used to fabricate imitation foods such as synthetic meats were evaluated for stimulative or inhibitory effects on the growth of Clostridium perfringens. Growth rate and extent were measured in thioglycolate medium without dextrose. This liquid medium contains Trypticase (BBL) which served as the protein control. For comparison, various soy proteins, synthetic meats, beef, turkey, sodium caseinate, and combinations of each were substituted for Trypticase. Meat loaf systems were also employed to determine the effects of protein additives to meat under actual meat loaf conditions. Growth of C. perfringens type A, strain S40, was measured in the respective media at 45 C at a pH of 7.0 and an E(h) of below -300 mv. Viable populations were enumerated by agar plate techniques on Trypticase-sulfite-yeast-citrate-agar incubated anaerobically (90% N(2)-10% CO(2)) for 18 hr at 35 C. When compared to Trypticase, some soy proteins had stimulative effects on the growth of C. perfringens, whereas sodium caseinate and some soy proteins were inhibitory. In liquid medium in which meat or soy meat was the source of protein, there was a marked stimulation by beef, chicken, and soy beef. Soy chicken supported growth at a rate less than observed with Trypticase. Under actual meat loaf conditions, the addition of soy meat or protein additives to beef did not affect the growth of C. perfringens. The addition of protein additives to turkey meat loaves significantly enhanced the rate of growth of C. perfringens. The stimulative effects of some soy proteins are significant in relation to control of foodborne disease.