Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “LACTOGLOBULINS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,261 records · Page 70Linked to original sources

Determination of effects of milk protein genotype on production traits of Israeli Holsteins.

Genotypes of 112 Israeli Holstein sires were determined for beta-lactoglobulin and kappa-casein by restriction fragment length polymorphism analysis of amplified DNA. Frequencies of the A alleles were .89 and .52 for kappa-casein and beta-lactoglobulin, respectively. Genotype frequencies were in accordance with Hardy-Weinberg equilibrium. Two models were used to test the effect of these loci on production of milk, fat, and protein and on fat and protein percentages. The dependent variable in the first model was production of 84,593 daughters of 110 genotyped sires, and the independent variables were herd-year-season, sire genotype for beta-lactoglobulin and kappa-casein, the interaction of the two loci, and sire nested within genotype. In the second model, the dependent variable was individual animal model genetic evaluations of 111 sires for production traits, and milk protein genotypes were the independent variables. The only significant effect of genotype with both models was the interaction of the two loci on fat percentage. When sires, rather than cows, were genotyped, the contrasted groups differed by only one-half of the genotype effect, but the residual variance was reduced.

Alleles↗

Association between milk protein genetic variants and genetic values of Canadian Holstein bulls for milk yield traits.

The kappa-casein, beta-casein, and beta-lactoglobulin genotypes of 566 bulls were identified by polymerase chain reaction. The associations of these milk protein types with the daughter yield deviations of the 566 bulls for milk, fat, and protein were examined with a mixed model analysis using an animal model. The results suggest that kappa-casein and beta-casein loci had no significant effects on ETA of the bulls for milk, fat, and protein. The effect of beta-lactoglobulin on ETA of protein approached significance. Results suggest that increasing the frequency of the A variant of beta-lactoglobulin in young bulls entering progeny testing improves ETA for protein of the bulls, but the expected improvement is limited.

Animals↗

Evaluation of the residual antigenicity of dairy whey hydrolysates obtained by combination of enzymatic hydrolysis and high-pressure treatment.

Dairy whey was hydrolyzed for 15 min with five food-grade enzymes (Alcalase, Neutrase, Corolase 7089, Corolase PN-L, and Papain) at atmospheric pressure (0.1 MPa) and in combination with high pressure (HP) at 100, 200, and 300 MPa, applied prior to or during enzymatic digestion. The peptide profile of the hydrolysates obtained was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and their residual antigenicity was assessed by immuno-blotting with anti-beta-lactoglobulin monoclonal antibodies and the sera from pediatric patients allergic to cow's milk proteins. Moreover, to evaluate the presence of residual trace amounts of casein in bovine whey hydrolysates, immunoblotting with anti-cow's milk protein polyclonal antibodies was performed. SDS-PAGE analysis showed that HP treatment increased hydrolysis by the proteases assayed, especially when it was applied during the enzymatic digestion. Positive reactions at the band corresponding to beta-lactoglobulin were detected for Corolase PN-L and Corolase 7089 hydrolysates, except for those obtained under 300 MPa by the last protease. However, the immunochemical reaction was lower in the hydrolysis products obtained under HP than in those obtained at atmospheric pressure and after the HP treatment. On the contrary, no residual immunochemical reactivity associated with beta-lactoglobulin was observed in the hydrolysates obtained by Alcalase and Neutrase under HP, and none was observed in any of the hydrolysis products obtained by Papain. The presence of traces of casein was not significant. These results suggest that HP combined with selected food-grade proteases is a treatment that can remove the antigenicity of whey protein hydrolysates for their use as ingredients of hypoallergenic infant formulae.

Animals↗

[Oral challenge with cow's milk in patients with IgA nephropathy--estimation of serum antibodies to cow's milk protein].

The author investigated the serum levels of antibodies against casein, beta-lactoglobulin and lactalbumin before and after challenging with cow's milk in 35 patients with IgA nephropathy, 18 with primary glomerulonephritis except for IgA nephropathy (GN control) and 11 healthy volunteers (H control). Blood samples were obtained at fasting, and at 30, 60, 120 and 180 min after oral challenging with 400 ml of cow's milk. IgA and IgG anti-cow's milk proteins antibodies were analyzed by ELISA. The same challenge was tested after administration of the antiallergic agent, sodium cromoglycate (SCG), in 11 patients with IgA nephropathy and 4 H controls. Serum levels of IgA anti-casein, -beta-lactoglobulin and lactalbumin antibodies in patients with IgA nephropathy were significantly higher than in control groups before challenging. However, those of IgG antibodies were not. The percent change of antibody titer after challenging with cow's milk did not elevate in any group, except for the level of IgA anti-beta-lactoglobulin antibody at 60 min in IgA nephropathy. Cases in which challenging produced marked elevation above the M + 2SD of the levels found in H control were expressed as "positive". The number of "positive" cases was 16 (45.7%) with IgA nephropathy, but none with GN control. There was no significant correlations between "positive" and "negative" cases with IgA nephropathy in clinical manifestations. In 3 out of 4 "positive" patients with IgA nephropathy, the levels of IgA antibody were suppressed after administration of SCG. It is concluded that the serum levels of IgA antibodies against cow's milk proteins are significantly elevated in IgA nephropathy, and are inhibited in elevation after oral challenge with cow's milk by administration of an antiallergic agent in some patients with IgA nephropathy.

Adult↗

Protein adsorption at solid-liquid interfaces: Part III--Adsorption from ternary protein mixture.

Simultaneous adsorption of bovine serum albumin (BSA), beta-lactoglobulin and gelatin from aqueous solutions of their ternary mixture to the alumina-water interface has been studied as a function of protein concentration at different values of pH, ionic strength, temperature and weight fraction ratios of proteins. At a fixed weight fraction of beta-lactoglobulin, preferential adsorption (gamma w(lac)) of this protein significantly depends on the amounts of BSA and gelatin present in the solution before adsorption. At higher ranges of protein concentrations, extent of adsorption (gamma w(ser)) of BSA decreases sharply with increase of gamma w(lac) until gamma w(ser) becomes significantly negative, thereby indicating that beta-lactoglobulin and water preferentially adsorbed at the interface are responsible for complete displacement of BSA from the surface. On the other hand, adsorption (gamma w(gel)) of gelatin under similar situation increases mutually with increase in the values of gamma w(lac) in many systems. In few systems, gamma w(gel) also decreases with increase of gamma w(lac) depending upon solution parameters. At pH 5.2, increase of ionic strength and temperature, respectively, increases the extent of adsorption of each protein in the mixture considerably. Extents of adsorption of all proteins are observed to increase when pH is changed from 5.2 to 6.4. The affinities of different proteins in the mixture are expressed in unified scales either in terms of maximum extents of total adsorption or in terms of standard free energies of adsorption of protein mixtures with respect to surface saturation.

Adsorption↗

Children with newly diagnosed insulin dependent diabetes mellitus have increased levels of cow's milk antibodies.

We studied antibodies to cow's milk, beta-lactoglobulin and gliadin with enzyme-linked immunosorbent assay in the sera of 91 children with insulin dependent diabetes mellitus (IDDM); 36 of them were newly diagnosed. The children with newly diagnosed IDDM had significantly higher levels of IgA antibodies to cow's milk and to beta-lactoglobulin, and IgG antibodies to beta-lactoglobulin than 100 age-matched controls. We infer that either the pattern of cow's milk consumption is altered in children who will have IDDM, or their immunological reactivity to proteins in cow's milk is enhanced, or the permeability of their intestines to cow's milk protein is higher than normal.

Animals↗

Specific antigen exclusion and non-specific facilitation of antigen entry across the gut in rats allergic to food proteins.

The intestinal absorption of ovalbumin and beta-lactoglobulin was measured in Hooded Lister rats which had previously been made allergic to ovalbumin, and in unimmunized controls. The antigens were introduced both together and separately into closed intestinal loops. Absorption of free ovalbumin, but not beta-lactoglobulin, was reduced in rats with anti-ovalbumin antibody, demonstrating antigen-specific immune exclusion despite the presence of reaginic antibody. In contrast, the absorption of beta-lactoglobulin was enhanced by the presence of ovalbumin in rats with IgE anti-ovalbumin, but not in unimmunized controls. These results suggest that macromolecular absorption may be increased in an antigen non-specific way in food allergy.

Animals↗

Atopic dermatitis: role of food and house dust mite allergens.

OBJECTIVE: The aim of this study was to evaluate the humoral immune response to cow milk (CM) protein, soya protein, and house dust mites in a group of 64 CM-fed infants, who had atopic dermatitis as the sole atopic manifestation, by measuring not only IgE but also specific IgG antibodies (Ab) against bovine beta-lactoglobulin, soya flour aqueous extracts, and Der P1 antigens. METHODS: A CM-free diet (Nan HA, Nestle) was given to these 64 CM-fed infants and the sensitivity to CM proteins was established by a positive challenge test with the offending food in improved infants. The serum was obtained just before the start of the CM-free diet, at the first consultation. The patients were classified into two groups according to their clinical response to the hypoallergenic formula. RESULTS: Thirty-one infants (group 1) improved dramatically (positive challenge test), and 33 (group 2) did not improve with the exclusion diet but did improve after eviction of dust-producing items in the environment. The two groups were different in terms of their total IgE immunoglobulin concentration (higher in group 1, P < .05) and concentration of specific IgE Ab against CM protein (more frequent in group 1, P < .01). The IgG Ab concentrations against beta-lactoglobulin, the major CM antigen (P < 10-4), and against soya protein (P < .01) were significantly more elevated in the group improved by the diet, with a threshold above which the response to the exclusion diet could be predicted as positive. On the contrary, the level of specific IgG Ab against house dust mites was four times higher in group 2 than in group 1. Twenty-nine of the 33 infants of group 2 improved after eviction of dust-producing items in the environment. CONCLUSIONS: It is proposed that specific IgG Ab concentrations against beta-lactoglobulin, soya protein, and Der P1 antigen be determined in infants and children suffering from atopic dermatitis as a means of predicting the response to an exclusion diet, and a possible role of house dust mites in the pathogenicity of the disease is suggested.

Animals↗

Milk protein synthesis, gene expression, and hormonal responsiveness in primary cultures of mammary cells from lactating sheep.

A ruminant mammary cell culture that accurately reproduces mammary function in vitro would be a valuable tool in studies of ruminant lactation. With this in mind, we have examined milk protein synthesis and secretion, milk protein mRNA abundance, and hormonal responsiveness in primary cultures of mammary acini from lactating sheep. alpha- and beta-casein protein synthesis, beta-lactoglobulin synthesis, and alpha-casein, beta-casein, and beta-lactoglobulin secretion are maintained at high levels for 8 h in culture, but then decline to approximately 25% of maximal rates between 8 and 24 h in culture, whereas synthesis of other proteins remains unaltered. The relative abundance of alpha-S1-casein, beta-lactoglobulin, and alpha-lactalbumin mRNAs similarly decline between 8 and 24 h in culture. Extracellular labeled alpha-casein is increased fourfold in the presence of fetal calf serum (FCS). In total, FCS alters the abundance of 47 of 68 secreted proteins detected by two-dimensional electrophoresis. However, FCS and lactogenic/galactopoietic hormones had no effect on the rate of decline of mammary function and did not promote any regaining of function when present for up to 9 days in culture. These results suggest that providing its limitations are recognized, this primary cell culture system may be useful in studying some aspects of ruminant mammary function in vitro.

Animals↗

Monitoring Protein Fouling of Metal Surfaces via a Quartz Crystal Microbalance.

A quartz crystal microbalance (QCM) has been used to study the fouling of chromium and hydrophobically modified gold surfaces when heated with milk proteins. Solutions of pure beta-lactoglobulin and a commercial skimmed milk powder were studied at 3 wt%, neutral pH, and before and after heating the solutions to 80 degrees C. The ease of removal of the adsorbed protein by rinsing with buffer and 1 wt% Tween 20 was also studied. The beta-lactoglobulin behaved rather similarly on the hydrophobic gold and chromium surfaces: Tween 20 was not particularly effective in removing this protein after heating. On the other hand, Tween 20 seemed more efficient at removing the heated skimmed milk protein from the hydrophobic gold surface, but less efficient at removing the skimmed milk from the chromium surface (which also exhibited the highest adsorbed amounts of either protein). On chromium, trypsin followed by buffer removed almost all the beta-lactoglobulin but had little effect on the adsorbed layers from skimmed milk. These changes are interpreted in terms of the hydrodynamic thickness of the adsorbed films and lead to the conclusion that the QCM is a highly sensitive way of monitoring adsorbed film properties during heating, cooling, and detergent action. Copyright 2000 Academic Press.

Journal Article↗

Hydrophobic interaction chromatography in alkaline pH.

Hydrophobic interaction chromatography is a very powerful protein purification technique which is dependent on strong salting-out salts to increase the hydrophobic interactions between the protein and the ligand. Ammonium sulfate is the salt most commonly used for this purpose, but it cannot be used at very alkaline pH. Monosodium glutamate was therefore tested as a salt for hydrophobic interaction chromatography at pH 9.5. When ribonuclease A, ovalbumin, and beta-lactoglobulin were individually applied to a phenyl superose column in 2 M monosodium glutamate, all three proteins bound to the column and could be subsequently eluted by decreasing the salt concentration. Using this salt, it was possible to separate commercially obtained beta-lactoglobulin into authentic protein and contaminants and to purify the individual proteins from a mixture of ovalbumin and beta-lactoglobulin. These results demonstrate that monosodium glutamate is a useful salt for hydrophobic interaction chromatography. Guanidine and sodium sulfate and sodium aspartate were also examined at the same pH, demonstrating that they also resulted in the binding and elution of the proteins examined.

Aspartic Acid↗

Purification and characterization of the major whey proteins from the milks of the bottlenose dolphin (Tursiops truncatus), the Florida manatee (Trichechus manatus latirostris), and the beagle (Canis familiaris).

The major whey proteins of the milks of the dolphin, manatee, and beagle were purified by gel filtration and ion exchange chromatography and characterized and identified by molecular weight determination, amino acid analysis, N-terminal sequencing, and activity measurements. The major whey protein components from all three species were found to be monomeric beta-lactoglobulins. These proteins were all active in binding retinol. Dolphin milk contained two beta-lactoglobulins (designated 1 and 2) which showed a slight difference in molecular weight and considerably divergent N-terminal sequences, whereas the other milks only contained a single form of beta-lactoglobulin. alpha-Lactalbumins were purified from dolphin and dog milks and were active in promoting lactose synthesis by bovine galactosyltransferase. The dolphin protein had an N-terminal sequence more similar to ruminant alpha-lactalbumins than to those known from other species. Although alpha-lactalbumin activity has been detected in manatee milk at low levels, the corresponding protein was not isolated. In addition, dog milk was found to contain high levels of lysozyme (greater than 1.0 mg/ml), which were identified by activity and sequencing. The functional and evolutionary implications of these results are discussed.

Amino Acid Sequence↗

Association of serum IgA antibodies to milk antigens with severe atherosclerosis.

The presence of antibodies of the IgA class against dietary antigens (bovine IgG (BGG), beta-lactoglobulin, casein, alpha-lactalbumin and xanthine oxidase, chicken ovalbumin and crude gliadin) was checked in the sera of 23 severely atherosclerotic subjects (ATS) and 20 highly selected controls (C). In these subjects an association between serum IgA levels and atherosclerosis had previously been shown. Determinations were performed by a micro-ELISA method and results were expressed as absorbances at 405 nm x 1000. Higher levels of IgA antibodies were found in ATS with respect to C against beta-lactoglobulin (respectively, 113.4 +/- 152.4 (1 SD) vs. 40.0 +/- 34.2; P less than 0.005) and casein (69.8 +/- 35.5 vs. 52.4 +/- 27.5; P less than 0.05). There was no difference in IgG and IgM against these 2 proteins between the 2 groups. Significant differences of prevalence of IgA antibodies were found for the following antigens: beta-lactoglobulin (4 C and 16 ATS over the limit value of 51; P less than 0.002), xanthine oxidase (1 C and 9 ATS over 289; P less than 0.01), BGG (7 C and 17 ATS over 87; P less than 0.02) and casein (5 C and 14 ATS over 60; P less than 0.02). These data suggest an association between anti-milk IgA antibodies and atherosclerosis. Its relevance and significance deserves further investigation.

Aged↗

A quantitative in silico analysis calculates the angiotensin I converting enzyme (ACE) inhibitory activity in pea and whey protein digests.

Angiotensin I converting enzyme (ACE) inhibitory peptides can induce antihypertensive effects after oral administration. By means of an ACE inhibitory peptide database, containing about 500 reported sequences and their IC(50) values, the different proteins in pea and whey were quantitatively evaluated as precursors for ACE inhibitory peptides. This analysis was combined with experimental data from the evolution in ACE inhibitory activity and protein degradation during in vitro gastrointestinal digestion. Pea proteins produced similar in silico scores and were degraded early in the in vitro digestion. High ACE inhibitory activity was observed after the simulated stomach phase and augmented slightly in the simulated small intestine phase. The major whey protein beta-lactoglobulin obtained the highest in silico scores, which corresponded with the fact that degradation of this protein in vitro only occurred from the simulated small intestine phase on and resulted in a 10-fold increase in the ACE inhibitory activity. Whey protein obtained total in silico scores of about 124 ml/mg, compared to 46 ml/mg for pea protein, indicating that whey protein would be a richer source of ACE inhibitory peptides than pea protein. Although beta-lactoglobulin is only partially digested, a higher ACE inhibitory activity was indeed found in the whey (IC(50) = 0.048 mg/ml) compared to the pea digest (IC(50) = 0.076 mg/ml). In silico gastrointestinal digestion of the highest scoring proteins in pea and whey, vicilin and albumin PA2, and beta-lactoglobulin, respectively, directly released a number of potent ACE inhibitory peptides. Several other ACE inhibitory sequences resisted in silico digestion by gastrointestinal proteases. Briefly, the quantitative in silico analysis will facilitate the study of precursor proteins on a large scale and the specific release of bioactive peptides.

Amino Acid Sequence↗

Isoelectric point separation of proteins by capillary pH-gradient ion-exchange chromatography.

In the present work, isoelectric point (pl) separation of proteins by pH-gradient ion-exchange chromatography (IEC) on packed capillary columns is demonstrated. The development of a miniaturized flow-through pH probe for reliable pH monitoring of the column effluent, which was an important technical challenge for adapting this technique to capillary dimensions, was solved by designing a low microliter per minute flow rate housing to a commercially available micro pH probe. Highly linear outlet pH-gradients within the pH range 8.5-4.0 were obtained when applying simple inexpensive buffers consisting solely of piperazine, N-methylpiperazine and imidazole on 10 cm x 0.32 mm i.d. fused silica capillaries packed with anion-exchange poly(styrene divinylbenzene)-based macroporous materials, i.e. 10 microm Mono P from Amersham Biosciences and 10 microm PL-SAX from PolymerLabs. Furthermore, when using a pH-gradient from 6.8 to 4.3, both columns were able to baseline separate the A and B genetic variants of beta-lactoglobulin, which differ with two amino acid residues only, but the PL-SAX column provided almost a two-fold decrease in peak widths compared to the Mono P column. The influence of varying the buffer concentration, injection volume and column temperature on the peak widths and resolution of the beta-lactoglobulins was investigated, e.g. a 100 microl sample of dilute beta-lactoglobulins was injected directly on the column with practically no increase in peak width as compared to what obtained with conventional injection volumes. Finally, a pH-gradient from 6.8 to 4.3 was used to separate proteins in skimmed bovine milk on the PL-SAX column. The milk was simply diluted 1:10 (v/v) with water and filtrated before injection.

Chromatography, Ion Exchange↗

Evaluation of an association between gastrointestinal symptoms and cytokine production against common dietary proteins in children with autism spectrum disorders.

OBJECTIVE: To evaluate an association between cytokine production with common dietary proteins as a marker of non-allergic food hypersensitivity (NFH) and gastrointestinal (GI) symptoms in young children with autism spectrum disorders (ASD). STUDY DESIGN: Peripheral blood mononuclear cells (PBMCs) were obtained from 109 ASD children with or without GI symptoms (GI [+] ASD, N = 75 and GI (-) ASD, N = 34], from children with NFH (N = 15), and control subjects (N = 19). Diarrhea and constipation were the major GI symptoms. We measured production of type 1 T-helper cells (Th1), type 2 T-helper cells (Th2), and regulatory cytokines by PBMCs stimulated with whole cow's milk protein (CMP), its major components (casein, beta-lactoglobulin, and alpha-lactoalbumin), gliadin, and soy. RESULTS: PBMCs obtained from GI (+) ASD children produced more tumor necrosis factor-alpha (TNF-alpha)/interleukin-12 (IL-12) than those obtained from control subjects with CMP, beta-lactoglobulin, and alpha-lactoalbumin, irrespective of objective GI symptoms. They also produced more TNF-alpha with gliadin, which was more frequently observed in the group with loose stools. PBMCs obtained from GI (-) ASD children produced more TNF-alpha/IL-12 with CMP than those from control subjects, but not with beta-lactoglobulin, alpha-lactoalbumin, or gliadin. Cytokine production with casein and soy were unremarkable. CONCLUSION: A high prevalence of elevated TNF-alpha/IL-12 production by GI (+) ASD PBMCs with CMP and its major components indicates a role of NFH in GI symptoms observed in children with ASD.

Autistic Disorder↗

Site-directed tryptophan fluorescence reveals the solution structure of tear lipocalin: evidence for features that confer promiscuity in ligand binding.

The solution structure of human TL was deduced from the position of the emission peaks after site-directed tryptophan fluorescence (SDTF). The fluorescent amino acid tryptophan was sequentially substituted for each native amino acid in the sequence. Characteristic periodicities for eight beta-strands that comprise the beta-barrel and three alpha-helices were identified. The putative beta-strand I was relatively exposed to solvent, suggesting it does not participate in the formation of the beta-barrel. The beta-strands A and F contain beta-bulges. The average lambda(max) of emission maxima reveals that strand D is at the edge of the barrel and beta-strand H interacts with the main alpha-helical domain. On the basis of the SDTF data, a 3D homology model was constructed for TL and compared to the known crystallographic structures of RBP and beta-lactoglobulin. The small size and splayed open configuration of the E-F hairpin facilitate access of ligands into the cavity mouth of TL as compared to that of RBP with a long overhanging loop that restricts access. In the model of TL, four alanine residues are positioned in the binding site as compared to bulkier residues in the corresponding positions of beta-lactoglobulin. Substitution of A51, A66, A86 to Trp results in a 3-4-fold decrease in binding affinity. The data suggest that the smaller side chains of Ala provide more capacity in the cavity of TL than the bulkier side chains (I56, I71, V92) in the cavity of beta-lactoglobulin. The structural features provide an explanation for the promiscuous binding characteristics exhibited by TL. SDTF provides a general approach for determining the solution structure of many proteins and enhances homology modeling in the absence of high sequence identity.

Amino Acid Sequence↗

In vitro digestion of cow's milk proteins by duodenal juice from infants with various gastrointestinal disorders.

The hydrolysis of bovine alpha-lactalbumin, beta-lactoglobulin, and casein by duodenal juice from 20 infants (18 with normal exocrine pancreatic function, 2 with pancreatic insufficiency), aged 3-19 months was studied in vitro with the aid of electroimmunoassay and sodium dodecyl sulfate-poly-acrylamide gel electrophoresis. The results from the two methods were almost identical. Duodenal juice from infants with cow's milk protein intolerance (7), celiac disease (5), and unclassified gastrointestinal disorder (6) had the same capacity to hydrolyze the milk proteins. No hydrolysis occurred in the two patients with pancreatic insufficiency. The hydrolyzing capacity was not correlated with age in the actual age group. The hydrolysis of the milk proteins occurred at a considerably slower rate when the proteins were crude, as in cow's milk, adapted, or unadapted formula, than when they were in a purified form. About 1 mg of purified alpha-lactalbumin or beta-lactoglobulin, and about 30 mg of purified casein could be hydrolyzed per milliliter duodenal juice per minute. Corresponding figures for the hydrolysis of the various proteins in cow's milk were 0.03, 0.12, and 16.1 mg/ml duodenal juice/min. Preincubation (60 min) with gastric aspirate after adjusting pH to 4-5 did not change the results. In conclusion, the duodenal juice from infants with normal exocrine pancreatic function has a great ability to hydrolyze casein. Corresponding hydrolytic capacity for alpha-lactalbumin or beta-lactoglobulin is considerably lower.

Animals↗