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At least 793 records · Page 44Linked to original sources
PubMed1990

Expression and secretion of bovine beta-lactoglobulin in Saccharomyces cerevisiae.

A bovine beta-lactoglobulin (beta-LG) was expressed in Saccharomyces cerevisiae carrying bovine pre-beta-LG cDNA and secreted into its growth medium. The expression plasmid was constructed by inserting the whole coding region of the cDNA encoding pre-beta-LG between the promoter and terminator of the yeast glyceraldehyde 3-phosphate dehydrogenase gene of pYG100, a yeast expression vector. In the supernatant of the yeast growth medium, beta-LG with a native conformation was detected by sandwich ELISA, and its amount was estimated to be 1.1 mg/l. A Western-immunoblotting analysis revealed that beta-LG secrected in the growth medium had the same mobility as that of authentic bovine beta-LG. The N-terminal sequence was also identical with that of authentic mature bovine beta-LG.

Amino Acid Sequence↗
PubMed1990

Comparison between the antigenicity of native and unfolded beta-lactoglobulin.

The antibody binding sites (B-cell epitopes) on beta-lactoglobulin (beta-LG) were surveyed by assaying the reactivity of the tryptic fragments of beta-LG to mouse anti-beta-LG antiserum with ELISA. Four peptide fragments (the residues 21Ser-40Arg, 41Val-60Lys, 102Tyr-124 Arg, and 149Leu-162Ile) bound the antibodies. We considered that B-cell epitopes of beta-LG were included in these fragments. Furthermore, these four tryptic fragments were also reactive with the antiserum to RCM beta-LG. Therefore, the unfolding of the beta-LG molecule is considered not to influence the localization of the antibody binding sites on beta-LG.

Amino Acid Sequence↗
PubMed2004

Beta-lactoglobulin/polysaccharide interactions during in vitro gastric and pancreatic hydrolysis assessed in dialysis bags of different molecular weight cut-offs.

The effects of gum arabic, low methylated (LM) pectin or xylan at levels of 0 and 50 wt.% on beta-lactoglobulin (beta-lg) digestibility were studied as well as the interactions between the two macromolecules during in vitro hydrolysis. The proteolysis was performed in a system involving a two-step hydrolysis: either pepsin alone, or pepsin followed by a trypsin/chymotrypsin (T/C) mixture in dialysis bags with molecular weight cut-offs (MWCO) 1000 or 8000 Da. Digestibility was estimated by the N release and by a SDS-PAGE electrophoresis of retentates from the two dialysis bags after hydrolysis. Turbidimetric measurements monitored the structural evolution of mixtures during the two-step hydrolysis. Results showed that beta-lg was almost resistant to peptic digestion and that polysaccharides increased the N release despite a reduction of pepsin activity. This is due to the formation of electrostatic complexes between polysaccharides and beta-lg, which reduced beta-lg aggregation, increasing its solubility. The polysaccharides reduced significantly the beta-lg T/C digestibility as determined using a dialysis bag with a MWCO 1000 Da, without a modification of their enzymatic activities. No significant effect of polysaccharides on the beta-lg digestibility was detected using the dialysis bag with a MWCO 8000 Da. The electrophoresis pattern did not show differences in the profile of retentates in relation with the dialysis bag used. This suggests that non-specific interactions could occur during the second step of hydrolysis between polysaccharides and amino acids or peptides smaller than 8000 Da.

Chymotrypsin↗
PubMedDate not supplied

[Interdependence between milk productivity of cattle and a complex of loci of a coupled block of caseins and beta-lactoglobulin].

The complex lactoprotein markers, connected with the different level of milking capacity and fat percentage are found in cattle on the basis of experimental data. The high correlation is stated between selection of beta-lactoglobulin alleles and alleles of the coupled gene casein blocks on the levels of microevolution herds and macroevolution breeds.

Alleles↗
PubMed2001

Effect of environmental factors on the droplet size of o/w emulsion stabilised by beta-lactoglobulin.

The effect of environmental factors (protein concentration, pH, ionic strength) on emulsification properties of beta-lactoglobulin (beta-Lg) was analysed. The protein was obtained from phospholipoprotein-free whey 25-fold concentrated by ultrafiltration (10 kDa cut off) after precipitation of alpha-lactalbumin (alpha-La) with 6% trichloroacetic acid. The Sauter diameter D(vs) of oil droplets in the emulsion stabilised by beta-Lg was found to increase with increases in the protein concentration in the range of 0.5 to 2.0% and medium acidity in the pH range of 5.0 to 7.0. An increase in ionic strength in the range of 0 to 100 mM caused that the emulsification properties of the protein worsened as compared with control emulsion.

Cheese↗
PubMed2005

Micropreparative separation, fractionation, and peptide mapping of beta-lactoglobulin A and B variants by capillary electrophoresis.

The methodological aspects for the separation, fractionation, and peptide mapping by free zone capillary electrophoresis (CZE) of beta-lactoglobulin (beta-Lg) variants A and B were established. First, beta-Lg variants A or B were separated and fractionated by CZE. Then, the collected protein fraction was subjected to off-line tryptic digestion. Second, peptide mapping of the tryptic hydrolysates and peptide fraction collection were carried out by CZE. beta-Lg variants were separated and collected using an uncoated capillary (72 cm x 75 microm i.d.) in 0.05 M borate buffer containing 0.1% Tween 20 at pH 8.0 by applying 20 kV. By subjecting the capillary under pressure after a delay time of 15%, the protein was collected in a microvial containing digestion buffer. The most suitable conditions for the tryptic digestion of beta-Lg were established by monitoring the reaction products with CZE. A tryptic hydrolysis with an enzyme-to-substrate ratio (E/S) of 1/20 and incubation for 20 hr at 37 degrees C was found to result in the most suitable conditions. Peptides were separated and collected using an uncoated capillary (120 cm x 75 microm i.d.) in 0.15 M formic acid at pH 2.3 by applying 28 kV. Peptide maps were highly reproducible as shown by coefficients of variation of less than 0.89 and 5.42% for migration times and peak areas, respectively. Moreover, very good resolution of the peptide maps revealed the region in which the aberrant peptides of the beta-Lg variants may be located.

Chemical Fractionation↗
PubMed2006

IgE cross reactivity between reindeer and bovine milk beta-lactoglobulins in cow's milk allergic patients.

BACKGROUND: Allergic reactions to cow's milk are common in small children. One of the main protein allergens found in cow's milk is beta-lactoglobulin (beta-Lg). Reindeer and bovine milk both contain related beta-Lg proteins, but the allergenicity of reindeer beta-Lg has not previously been studied. The purpose of this study was to analyze the immunological cross-reactivity of IgE antibodies from children with cow's milk allergy to reindeer and bovine beta-Lg. METHODS: Sera from 17 children and a serum pool of 4 patients with elevated cow's milk-specific IgE were investigated. Beta-Lg from bovine and reindeer milk was isolated in native form and an enzyme-linked immunosorbent inhibition assay was developed. Bovine beta-Lg was used as a capturing antigen and the inhibiting effects of reindeer and bovine beta-Lg on the IgE binding were measured. RESULTS: Cross-reactivity patterns of bovine milk beta-Lg specific IgE to reindeer beta-Lg varied among patients. In general, reindeer beta-Lg showed significantly lower inhibition (mean 43%) of IgE binding to the capturing antigen than did bovine beta-Lg (mean 89%). In some patients, even high concentrations of reindeer beta-Lg only partly eliminated the IgE binding to bovine beta-Lg. CONCLUSIONS: The partial cross-reactivity of human anti-bovine IgE with reindeer beta-Lg suggests that it lacks important bovine epitopes and those that are recognized are only weakly bound.

Animals↗
PubMed1991

[An experimental study of a lactoglobulin preparation against opportunistic bacteria and salmonellae].

A preclinical study of seven batches of lactoglobulin, a new biological preparation against opportunistic bacteria and salmonellae, has been carried out. High antibacterial activity of the preparation with respect to the virulent forms of Salmonella typhimurium, Salmonella enteritidis, Pseudomonas aeruginosa, Klebsiella pneumoniae, Proteus vulgaris, Proteus mirabilis has been established. The preparation has been shown to be safe and nontoxic. The 4-year term of its storage at a temperature of 6 degrees +/- 4 degrees C has been substantiated.

Animals↗
PubMed1990

[Prospects of using controlled-action lactoglobulins in the treatment of acute intestinal infections and dysbacteriosis in infants].

The author summarizes the results of the preclinical study and clinical trial of the new biological drug lactoglobulin having an +anti-coli-proteus action. Shows that the drug holds promise in the treatment of infants with acute intestinal infections and dysbacteriosis as well as in the enrichment of lactic mixtures used for artificial feeding of premature children and babies referred to the risk group.

Animals↗
PubMedDate not supplied

[Anti-beta-lactoglobulin antibodies as an index of increased intestinal permeability in celiac disease].

IgG antibodies to beta-lactoglobulin (ABLG) were assayed in children with coeliac disease (20 at gluten-containing diet and 35 at gluten-free diet) and in 28 "gastrointestinal" controls. Pathologic levels of ABLG were found in 16 patients with active coeliac disease (80%). In these patients the ABLG mean value was significantly higher than that found in the controls (p less than 0.001). In coeliac subjects at gluten-free diet, normal levels of ABLG were found after 6 months of diet. The presence of ABLG in the majority of untreated coeliac patients may reflect an increased permeability of the intestinal mucosa during the active stage of the disease.

Adolescent↗
PubMed1989

Maternal immune status against beta-lactoglobulin and cow milk allergy in the infant.

Beta-lactoglobulin (BLG) is probably the major cow milk antigen. Serum levels of anti-BLG antibodies were determined prospectively in mothers. The results were analyzed according to the existence of allergic manifestations in infants during the first months of life. Mothers of babies who developed allergy had statistically lower IgG anti-BLG concentrations than mothers of infants who presented no symptoms (P less than .001). Together with IgE umbilical cord blood screening, determine maternal IgG anti-BLG concentrations can more clearly define the allergic risk in the infant.

Adult↗
PubMedDate not supplied

[Experience in the use of anti-colibacillus and Proteus lactoglobulin as a supplement to milk products in diet therapy at a specialized childrens' collective].

A new biologically active supplement (BAS) for infant food was tested at an Infant's Home. BAS-IG contains lactoglobulin, an immune preparation against colibacillus and Proteus. During the primary examination of the infants in the Infant's Home intestinal dysbacteriosis was revealed in 100% of the infants, clinical signs of dysbacteriosis were detected in 88.4% of the infants. Two successive courses of feeding the infants with products enriched with the new supplement resulted in a significant improvement of the microflora composition in them and in normalizing their clinical condition. At the same time positive changes in a number of immunological factors were recorded. The authors have recommended using BAS-IG for correction of dysbacteriosis in children at Infant's Homes.

Child Day Care Centers↗
PubMed1986

A mouse monoclonal IgE antibody anti bovine milk beta-lactoglobulin allows studies of allergy in the gastrointestinal tract.

A monoclonal IgE antibody directed against bovine milk beta-lactoglobulin (beta-LG) was produced by fusion of NSI myeloma cells with spleen cells of Balb/c mice immunized with alum-precipitated beta-LG. This antibody was found by radioimmunoassay to react with both native and aggregated beta-LG, but a positive passive cutaneous anaphylaxis reaction (PCA) was evident only with aggregated beta-LG. 1 ng of this purified antibody was capable of eliciting a PCA. The chemical and physical properties were characterized by amino acid and carbohydrate analysis and by ultracentrifugation. The epsilon-chain had an apparent molecular weight of 86,000 +/- 2,000 by polyacrylamide gel electrophoresis. An immediate hypersensitivity reaction within the gut was elicited by intravenous (i.v.) administration of the hybridoma ascitic fluid followed by feeding with aggregated beta-LG. Accumulation of liquid within the small intestine and diarrhoea were evident 30-90 min later. Intravenous injection of carbon particles revealed an increased permeability of the venulae from the submucosa and serosa. Histological examination showed oedema within the villae, without modification of the epithelium.

Animals↗
PubMed1976

Conformation of adsorbed gamma-globulin and beta-lactoglobulin. Effect of surface concentration.

The conformation of both adsorbed gamma-globulin and beta-lactoglobulin is dependent on surface concentration. Infrared bound fraction measurements show that the fraction of adsorbed carbonyl groups decreases as the amount adsorbed increases, while the ellipsometrically measured extension is higher for adsorption from higher concentration solutions. Similar studies with a cross-linked gamma-globulin preparation indicate that the native conformation in solution corresponds to an adsorbed conformation intermediate between those found at the extremes of high and low surface concentration.

Adsorption↗
PubMed1995

Jejunal response to beta-lactoglobulin in infants with cow's milk allergy.

Weaning is a transient period of life during which maternal proteins are replaced by foreign proteins. Concomitantly, in early postnatal life, both digestive and immune systems undergo a maturation process. Allergy to cow's milk protein may develop in human infants during weaning, determining digestive, respiratory, cutaneous or systemic symptoms. We studied the intestinal response to bovine milk beta-lactoglobulin (beta-LG) in infants with cow's milk allergy, first during the active phase, and then during the symptom-free stage. During the active phase, transepithelial transport of the beta-LG across the intestinal epithelial layer stimulated the sensitized subepithelial immune cells. This stimulation induced a rise in short-circuit current suggestive of an electrogenic chloride secretion and impaired protein handling by the epithelium. These findings underline the dual role of the epithelial layer in intestinal function: on one hand, it takes an active part in allowing dietary antigens to stimulate the submucosal system, and on the other hand becomes the target for mediators involved in food allergy.

Biopsy↗
PubMed1993

Unfolding/refolding studies on bovine beta-lactoglobulin with monoclonal antibodies as probes. Does a renatured protein completely refold?

We investigated whether any local moieties within a protein molecule could completely refold from the denatured state to regain the native conformation. Bovine beta-lactoglobulin (beta-LG) was denatured in the presence of guanidine hydrochloride (GdnHCl) as the denaturant. Renaturation of the denatured beta-LG was attempted by dialyzing to remove GdnHCl. The renatured molecules regained the same retinol binding activity as that of native beta-LG, and physicochemical studies also indicated that refolding of the denatured beta-LG had been almost completely successful. Local structural differences between the native and renatured beta-LG molecules were evaluated by using our panel of four anti-beta-LG monoclonal antibodies (anti-beta-LG mAbs). The structures of the epitope regions in native beta-LG recognized by two of these mAbs were the same as those in renatured beta-LG. However, it is notable that the binding properties of the other two mAbs to native beta-LG indicated a wide structural difference in the epitope regions between the native and renatured beta-LG. These regions unable to completely refold were the same as those that unfolded preferentially to the alpha-helix region, shown in the previous report (Kaminogawa, S., Shimizu, M., Ametani, A., Hattori, M., Ando, O., Hachimura, S., Nakamura, Y., Totsuka, M., and Yamauchi, K. (1989) Biochim. Biophys. Acta 998, 50-56). Complete refolding was never attained by several renaturation conditions such as quicker or slower removal of the denaturant, nor by additional oxidation treatment after reducing the disulfide bonds. These results suggest that some specific moiety(ies) in a protein molecule cannot return to the native conformation from a denatured state, even if the other moieties refold completely, and that such a conformational difference between renatured and native forms has no affect on the biological function of ligand binding.

Amino Acid Sequence↗
PubMedDate not supplied

[IgG subclasses against bovine alpha-lactalbumin and beta-lactoglobulin in infants fed with a seroprotein hydrolysate].

Prevention of food allergy in infancy has been the aim of important researches in the last years but many studies have produced conflicting conclusions. The use of hydrolysate formulas seems to be an helpful tool in prevention of cow milk protein allergy but confusion often remains about capability of small hydrolysate molecules to be "allergens" or "antigens". In order to clarify this point IgE, IgG and IgM as well as IgG subclasses against alfa-lactoalbumin (ALA) and beta-lactoglobulin (BLG) have been evaluated in 41 infants at risk for allergy and in 30 controls at the fourth month. The same evaluation has been done on their mothers. The 41 "at risk" children were fed with breast milk or with an hypoallergenic formula (Nidina HA, Nestlè) or both. The control children received an adapted formula. No difference between the two groups of children was found regarding IgM or IgG against ALA while antibodies against BLG were more frequently found in controls than in "at risk" children. Only one child in the group fed with Nidina HA developed specific IgE against whole milk. Therefore hydrolysate formula seems to be as antigenic (not allergenic) as adapted formula in respect of ALA while BLG contained in adapted formula seems to be a stronger immunogen. The pattern of specific IgG subclasses against ALA and BLG is different between the two groups of children because of the absence in "at risk" group of specific IgG2 and IgG3. As for the mothers, the presence in their sera of IgG against ALA or BLG seems to induce in infants a reduced response to the same antigen.

Albumins↗
PubMed1995

[Analysis of linkage between beta-lactoglobulin and J blood group system loci in cattle].

Linkage between loci controlling variants of beta-lactoglobulin and blood groups of the J system in cattle was studied by means of stochastic genetic methods reported earlier. The studies were conducted on a herd of Black Pied cattle improved with Holstein sires; population genetic data were analyzed. A plot for lod score was constructed, and point (r - 0.28) and interval estimations of the coefficient of recombination were obtained. The results are in good agreement with earlier reported data on other subjects.

Animals↗