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At least 1,531 records · Page 85Linked to original sources
PubMed1991

Estimation of milk protein gene frequencies in crossbred cattle by maximum likelihood.

A maximum likelihood method is presented to estimate the fraction of animals misclassified and breed effects for milk protein gene frequencies based on crossbred data. A simulation study indicates that the method provides estimates of gene frequencies that agree closely with the true values. Gene frequencies in the Dutch Black and White and the Dutch Red and White crossbred populations, based on data on 10,151 and 580 animals respectively, were estimated. Dutch Friesian and Holstein-Friesian breeds differ in gene frequencies for beta-casein and beta-lactoglobulin. Estimates for fractions misclassified are zero for alpha s1-casein, .09 for beta-casein and beta-lactoglobulin, and .12 for kappa-casein. Differences between Dutch Red and Whites and Red Holstein-Friesian breeds are small, and estimates for fractions misclassified are high but have high approximate standard errors. Compared with the Black and White breeds, the Red and Whites have a high kappa-casein B gene frequency.

Alleles↗
PubMed1992

Application of PhastSystem to the resolution of bovine milk proteins on urea-polyacrylamide gel electrophoresis.

Optimal conditions were established for alkaline urea-PAGE using modified precast, ultrathin gradient gels on the automated PhastSystem. Profiles of milk proteins showed that the caseins and whey proteins resolved extremely well. Major bands were observed for alpha s1-casein and beta-casein, and alpha s2-casein appeared as a well-resolved doublet. In contrast, kappa-casein separated from other caseins as a faint doublet, and purified kappa-casein appeared as one major and one minor band. Whey proteins (serum albumin, alpha-lactalbumin, beta-lactoglobulin) separated into broad bands resolved from each other and from the caseins. Partially (40%) dephosphorylated whole casein showed multiple bands for alpha s1-casein and beta-casein at different levels of phosphorylation. Separation of genetic phenotypes was observed for beta-lactoglobulin A and B; alpha s1-casein A, B, and C; and beta-casein A, B, and C. Electrophoretic patterns of milk proteins extracted from cheese samples varied among the different types of cheeses. Our modified procedure provides researchers with a rapid technique to separate both caseins and whey proteins on the same urea gel according to their charge to mass ratios.

Animals↗
PubMed1985

Gelation of the heat-induced complex between kappa-casein and alpha-lactalbumin.

Whey is a by-product of the manufacture of cheese from milk. The usual practice is to dispose of it, the usage of whey being not sufficiently developed, though it contains proteins of excellent quality such as beta-lactoglobulin and alpha-lactalbumin. Interaction between kappa-casein and whey protein was examined in order to form new food materials. Gelation of the heat-induced complex between kappa-casein and alpha-lactalbumin is described in this paper. alpha-Lactalbumin was easily separated from whey protein by the gel filtration technique on a Toyopearl HW-50 column at pH 6.0. Heat treatment facilitated the hydrolysis of a mixture of kappa-casein and alpha-lactalbumin by trypsin, alpha-chymotrypsin and pronase. Heat treatment at above 75 degrees C and a protein level of over 5% were needed to form gel in 35 mM phosphate buffer, pH 7.6, containing 0.4 M NaCl. The temperature was in agreement with that at which alpha-lactalbumin denatured and formed the complex with kappa-casein. Decrease of soluble protein concentration and increase of turbidity were induced with gelation. Gel was not formed when only kappa-casein or alpha-lactalbumin was heated under the appropriate conditions. It was considered that a kappa-casein-alpha-lactalbumin gel was formed from a complex of the two proteins by heat treatment. The breaking stress of kappa-casein-alpha-lactalbumin gel was less than that of kappa-casein-beta-lactoglobulin gel. If the pH was reduced to 5.8 after complex formation by the two proteins, gel was formed at a low protein concentration compared with that with no alteration of pH.

Caseins↗
PubMed2004

[Inter-laboratory evaluation studies for development of notified ELISA methods for allergic substances (milk)].

Extracts of sausage, sauce, cookie, cereal and pasta sauce spiked with milk standard protein at a level of 5-20 ng/mL as sample solutions were analyzed in replicate in 10 laboratories. Coefficients of variation (CVs) of the three ELISA methods using a Milk Protein Casein ELISA Kit (Casein kit), a Milk Protein Beta-Lactoglobulin ELISA Kit (Beta-Lactoglobulin kit) and a FASTKIT Milk ELISA Kit (Milk ELISA kit) were mostly below 10%. Mean recoveries of the milk standard protein from the food extracts were over 40% in the three ELISA methods with a few excertions. The recoveries of milk standard protein from the sauce extract in Casein kit were improved by adjusting the extract to neutrality before the Casein kit assay. The recoveries of milk standard protein from cookie, cereal and pasta sauce were improved by the increasing the amount of antibody coated in the Milk ELISA kit. The detection limits of all the ELISA methods were 1 ng/mL in sample solutions. These results suggested that the notified ELISA methods are reliable and reproducible for the inspection of milk protein levels in extracts of sausage, sauce, cookie, cereal and pasta sauce.

Allergens↗
PubMed1998

Detection of bovine milk proteins in soymilk by Western blotting.

A Western blotting method for the detection of whey milk proteins in commercial soymilks was applied to assess the food safety. Soy proteins and milk proteins were separated by SDS-PAGE in PhastSystem equipment. After the electrophoretic separation, immunodetection with anti-bovine alpha-lactalbumin and anti-bovine beta-lactoglobulin antisera was performed. Adulteration with bovine protein in percentages of 0.1% in soy protein can be detected. Western blotting of bovine alpha-lactalbumin and bovine beta-lactoglobulin was applied to detect adulteration by bovine milk proteins in different soymilks: powdered soymilk and soy infant formulas.

Animals↗
PubMedDate not supplied

[Cow-milk's protein allergy].

Milk contains more than 40 proteins and all of them may act like human species antigens. The main allergens are beta lactoglobulin, casein, alpha lactoalbumin and seroalbumin; beta lactoglobulin is a protein not existing in human species and is found in maternal milk in minimal quantities (mcg) due to milky products ingested by the mother, these small quantities are responsible of the highest number of sensitizations to this protein. This article reviews the allergy to the cow-milk's protein, also, a critical route to its diagnosis and management is planted.

Algorithms↗
PubMed1988

Structural studies, localization in tissue and clinical aspects of human endometrial proteins.

Two human endometrial proteins, PP12 and PP14, are abundant in human amniotic fluid which is an excellent source for purification. In SDS-PAGE, purified PP12 migrates as several immunoreactive bands from 17,000 to 34,000, all having the same N-terminal amino acid sequence of Ala-Pro-Trp-Gln-Cys-Ala-, and all of them binding IFG-I. PP14 migrates at 28,000, and its N-terminal sequence is Met-Asp-Ile-Pro-Gln-Thr-Lys-Gln-Asp-Leu-Gln-Leu-Pro-Lys-Leu-Ala-Gly-Thr- Trp-His-Ser-Met-. There is a 59% identity between this sequence and that of horse beta-lactoglobulin, and also between PP14 and beta-lactoglobulins of various other species. PP14 and human retinol-binding protein show a 23% sequence identity, and the amino acid residues -Gly-Thr-Trp- at positions 17-19 of PP14 are identical with the corresponding residues of human retinol-binding protein. This site is assumed to play a part in the binding of retinol. An additional sequence identity (32%) is reported here for PP14 and protein BG, a 182 amino acid protein deduced from a 700-base pair cDNA clone isolated from the olfactory neuroepithelium of the frog. Sequence homology is also reported here between PP14 and insecticyanin, a camouflage-associated biliprotein in insects. The sequence of PP14 is therefore homologous to members of a family of proteins that bind and transport biologically active small molecules. Clinical studies have indicated an increase of PP12/IGF-bp and PP14 in the endometrium with advancing secretory changes. PP12/IGF-bp is also found in preovulatory follicular fluid. In hyperstimulated cycles of infertile women undergoing in-vitro fertilization, the serum PP12/IGF-bp concentration rises as multiple follicles mature, and luteinized granulosa cells contain this protein. In non-pregnant women, elevated values have been found in patients with advanced ovarian cancer and primary liver cancer. During pregnancy the serum PP12/IGF-bp concentration rises above the level in non-pregnant women around Week 8 of gestation. Abnormally high levels are seen in patients with pre-eclampsia and, in the third trimester, there is an inverse correlation between the maternal serum PP12/IGF-bp level and fetal weight. From these studies it is likely that a relationship exists between PP12/IGF-bp, the metabolism of IGFs and fetal growth. In non-pregnant women, serum PP14 concentrations appear to reflect endometrial secretory function. This is indicated by cyclic changes in the PP14 concentration in endometrial tissue and by the rising PP14 values in the late luteal phase.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMedDate not supplied

Determination of sulfur amino acids and tryptophan in foods and food and feed ingredients: collaborative study.

Samples of 4 foods, 1 animal feed, isolated soy protein, and beta-lactoglobulin were analyzed by 9 laboratories to determine concentrations of cysteine as cysteic acid, methionine as methionine sulfone, and tryptophan. Sulfur amino acids were determined by AOAC method 43.A08-43.A13 for food and feed ingredients, in which samples are oxidized with performic acid before protein hydrolysis with 6N HCl. Tryptophan was determined after protein hydrolysis with 4.2N NaOH. In both methods, free amino acids were separated by ion-exchange or reverse-phase chromatography. Each laboratory was provided with detailed methods and with sealed vials containing solutions of standards. Samples were analyzed in duplicate, and variation between laboratories was determined. Coefficients of variation between laboratories for the 6 samples ranged from 5.50 to 11.8% for methionine as methionine sulfoxide, 8.59 to 17.3% for cysteine as cysteic acid, and 3.87 to 16.1% for tryptophan. Amino acid recoveries were determined by analysis of beta-lactoglobulin and were based on expected levels of each amino acid obtained from amino acid sequence data. The mean recovery of cysteine was 97% with a range of 88-119%. For methionine, mean recovery was 98% (range 89-115%) and for tryptophan, 85% (range 59-102%). Method 43.A08-43.A13 for food and feed ingredients has been adopted official first action for determination of cysteine and methionine in processed foods. The alkaline hydrolysis method has been adopted official first action for determination of tryptophan in foods and food and feed ingredients.

Amino Acids, Sulfur↗
PubMed1985

[Linkage relationship among loci determining genetic variants of serum and milk proteins in cattle].

Special methods allowing usage of inadequate pedigrees were employed to examine linkage among the milk protein loci alpha s1-casein, beta-casein, chi-casein and beta-lactoglobulin, and the loci for serum amylase, ceruloplasmin and transferrin. Linkage was evident between the alpha s1-casein and beta-casein loci, the alpha s1 and chi-casein loci, the beta-casein and chi-casein loci, also amylase and transferrin loci. Recombination fractions for these corresponding combinations were 0.00; 0.00; 0.00 and 0.30. Weak linkage (recombination fraction being 0.46; 0.44 and 0.42) between the beta-lactoglobulin and beta-casein loci, the amylase and ceruloplasmin loci, ceruloplasmin and transferrin loci is supposed.

Animals↗
PubMedDate not supplied

Oxidation and hydrolysis determination of sulfur amino acids in food and feed ingredients: collaborative study.

Samples of 6 food and feed ingredients and a purified protein, beta-lactoglobulin, were analyzed by 7 laboratories to determine the concentrations of cysteine as cysteic acid and methionine as methionine sulfone. Samples were oxidized by reaction with performic acid before hydrolysis with 6N HCl. The free amino acids were then separated and measured by ion-exchange chromatography on dedicated amino acid analyzers. Each laboratory was provided with a detailed method as well as sealed vials containing solutions of standards. For the determination of cysteine as cysteic acid, the coefficients of variation between laboratories for duplicate samples ranged from 7.13 to 10.8% for the 6 ingredients. For the determination of methionine as methionine sulfone, the coefficients of variation between laboratories for duplicate samples ranged from 1.18 to 12.8% for the 6 ingredients. Cysteine and methionine recoveries were determined by analysis of beta-lactoglobulin and were based on expected levels of each amino acid from amino acid sequence data. The mean recovery of cysteine was 95% with a range of 91-101%. The mean recovery of methionine was 101% with a range of 98-106%. This method has been adopted official first action.

Amino Acids, Sulfur↗
PubMed1985

[Quantitative differences between genetic variants of milk proteins in Cholmogor cattle].

The quantitative determination of genetical variants A and B of beta, kappa-caseins (beta-Cn, kappa-Cn), beta-lactoglobulin (beta-Lg) in Cholmogor cow's milk was carried out by means of polyacrylamide gel electrophoresis and direct densitometrication. In all milk proteins of heterozygous cows with beta-CnAB, kappa-CnAB, beta-LgAB the variant A content was higher than that of variant B (P less than 0.001). The variant A of beta-casein was 0.380 g/100 ml (54.6%), B-0.316 g/100 ml (45.4%); of kappa-casein A-0.208 g/100 ml (58.3%), B-0.149 g/100 ml (41.7%); of beta-lactoglobulin A-0.143 g/100 ml (54.8%), B-0.118 g/100 ml (45.2%). The alleles beta-CnA, kappa-CnA, beta-LgA ensure higher quantity of protein than beta-CnB, kappa-CnB, beta-LgB alleles.

Alleles↗
PubMed1983

[Intolerance to cow's milk. Study of specific immunoglobulin E].

IgE's specifically directed against alpha-lactalbumin, beta-lactoglobulin and casein were evaluated in the sera of 164 children aged between 8 days and 3 years, suspected of intolerance to cow's milk. In addition to these three RAST's for single allergens, a "total cow's milk proteins" RAST was performed. Intolerance was detected in 107 out of 180 sera tested, with at least one of the RAST's being positive. The two specific allergens most frequently involved were alpha-lactalbumin and beta-lactoglobulin. However, these proved curiously less sensitive than the "total allergen", which makes the use of these tests of little interest as a rule. A highly significant positive correlation was found between total IgE's and positivity of the four RAST's.

Animals↗
PubMed1984

Immune response patterns in coeliac disease. Serum antibodies to dietary antigens measured by an enzyme linked immunosorbent assay (ELISA).

Serum IgG, IgA and IgM activities to wheat, egg and cow's milk antigens were measured by an ELISA method in children and adults with coeliac disease (CD). In untreated patients, the IgA activity was characteristically raised to gluten antigens but often also to proteins from egg or cow's milk. Setting the upper reference range for gluten antibodies as the highest IgA reading obtained in healthy controls and patients with other intestinal disorders, IgA measurements afforded virtually 100% diagnostic sensitivity and specificity and detected 94% of children and 80% of adults with untreated CD. Such measurements, therefore, represent a valuable adjunct in the diagnosis of this disease. IgA activity to beta-lactoglobulin, casein or ovalbumin higher than the normal 95 percentile was found in 44-89% of untreated patients. Reduction of these antibody titres seemed to reflect relatively well the response to treatment with a gluten free diet, particularly the activity to beta-lactoglobulin. Monitoring of IgA antibodies to dietary antigens other than gluten may therefore be of particular importance in the follow-up of CD patients.

Adolescent↗
PubMed1983

[Cefacetril in treatment of clinical bovine mastitis].

The dynamic of the reconvalescence process was followed up in the udder of cows treated with the intramammary preparation Cefacetril. Complete therapeutic effect was recorded with 93.10 per cent of the cases, elimination of the infection -- with 86 per cent, and normalization of the cell content -- with 37.93 per cent. It was also established that during recovery the chlorine content of milk dropped, while lactose rose. The percent content of the protein fractions changed, whereupon the serum albumin and the immunoglobulins decreased, and the beta-lactoglobulin and the gamma-lactoglobulin increased.

Animals↗
PubMed1982

Detergent activation of the binding protein in the folate radioassay.

A minor cow's whey protein associated with beta-lactoglobulin is used as binding protein in the competitive radioassay for serum and erythrocyte folate. Seeking to optimize the assay, we tested the performance of binder solutions of increasing purity. The folate binding protein was isolated from cow's whey by means of CM-Sepharose CL-6B cation-exchange chromatography, and further purified on a methotrexate-AH-Sepharose 4B affinity matrix. In contrast to beta-lactoglobulin, the purified protein did not bind folate unless the detergents cetyltrimethylammonium (10 mmol/L) or Triton X-100 (1 g/L) were present. Such detergent activation was not needed in the presence of serum. There seems to be a striking analogy between these phenomena and the well-known reactivation of certain purified membrane-derived enzymes by surfactants (lipids/detergents).

Detergents↗
PubMedDate not supplied

[Initial kinetics of milk protein hydrolysis by chymotrypsin].

The kinetics of the initial stages of hydrolysis of alpha- and beta-caseins, alpha-lactalbumin, beta-lactoglobulin, and bovine serum albumin was studied quantitatively by electrophoresis. The hydrolysis rates of caseins (demasked polypeptide chains) exceeded the rates of the degradation of milk whey proteins limited by the protein globule demasking by more than two orders of magnitude. Even relatively accessible for hydrolysis globular proteins (beta-lactoglobulin and BSA) were hydrolyzed by the one-by-one mechanism. The maximum value of the ratio between the rates of the peptide chain demasking and the protein globule hydrolysis was 0.0035.

Chymotrypsin↗
PubMed1997

Glycodelins GdA and GdS modified by 3-hydroxyphthalic anhydride inhibit gp120-CD4 binding and HIV-1 infection in vitro.

Bovine beta-lactoglobulin chemically modified with 3-hydroxyphthalic anhydride (3HP) was recently shown, at nanomolar concentrations, to block the binding site on CD4 for the HIV surface glycoprotein (gp120), potentially inhibiting HIV transmission. Human glycodelin has sequence homology with bovine beta-lactoglobulin and appears as different glycoforms in endometrium (GdA) and seminal plasma (GdS). We studied the anti-HIV effects of chemically modified GdA and GdS on both the infection of MT-2 cells by HIV-1IIIB, and the infection of peripheral blood mononuclear cells by the primary HIV isolate THA/93/051 belonging to subtype E. Whereas the native proteins were inactive when tested at physiologic concentrations, nanomolar concentrations of either 3HP-GdA or 3HP-GdS inhibited the production of HIV nucleocapsid p24, cytopathic effects of HIV-1IIIB, and infection of peripheral blood mononuclear cells by the primary HIV isolate THA/93/051. Moreover, both modified proteins inhibited gp120-CD4 binding, 3HP-GdS being more potent than 3HP-GdA (p = 0.0042). Because GdA and GdS have the same major protein core, the observed difference in gp120-CD4 binding must depend on the specific glycoform. In view of the previously reported contraceptive activity of GdA, the observed anti-HIV activity induced by its chemical modification should be of special interest in the development of antiviral strategies that may also have contraceptive effects.

Anti-HIV Agents↗
PubMed1998

Gene expression in the mammary glands of transgenic animals.

The gene encoding the milk protein beta-lactoglobulin in sheep is expressed in the mammary gland in a tissue-specific manner during pregnancy and lactation. The unmodified sheep gene behaves appropriately in transgenic mice, and we have shown that many of the cis-acting elements that mediate this pattern of expression are located in the proximal 400 bp of the promotor. Using a combination of approaches we have identified a number of discrete cis-acting elements and their corresponding trans-acting factors that control the responsiveness of this gene in vivo. The beta-lactoglobulin promoter elements can be used to target the expression of foreign genes to the mammary gland in transgenic mice. We have used this approach in basic studies of mammary gland biology and for the production of therapeutic proteins in the milk of transgenic animals. In these circumstances, however, the promoter rarely functions optimally, and it may even be silenced; consequently, we have had to develop a number of strategies to overcome this problem. Nevertheless, foreign proteins do appear to be appropriately post-translationally modified when they are expressed in the mammary gland.

Animals↗