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Association of xanthine oxidase with the bovine milk-fat-globule membrane.

ABSTRACT: 1. The catalytic properties of xanthine oxidase in bovine milk (EC 1.2.3.2) are dependent on the state of the enzyme, i.e. whether free or bound to the fat-globule membrane. Oxidase activity of the membrane-bound enzyme towards NADH is enhanced relative to that towards xanthine. This reflects a change in the relative K(m) values and enables the ratio of xanthine to NADH oxidase activities (X/N) to be used as a parameter for the relative amounts of free and membrane-bound xanthine oxidase in milk fractions. 2. Chromatography of buttermilk on Sepharose 2B yielded an excluded fraction, BM(1), with xanthine oxidase activity. The remaining xanthine oxidase activity was eluted as a single broad peak. This was further resolved on Sephadex G-200 into an excluded fraction, BM(2), and free xanthine oxidase. Fractions BM(1) and BM(2) had X/N values in the range 45-65, which is characteristic of membrane-bound xanthine oxidase. Purified xanthine oxidase has a mean X/N value of 110.3. Addition of fraction BM(1), heated to remove associated enzyme activities, to purified xanthine oxidase progressively enhanced its NADH oxidase activity to a value where its X/N value was characteristic of membrane-bound xanthine oxidase. This was shown to be due to binding of free enzyme to heated fraction BM(1). The binding constant and stoicheiometry were determined. 4. Proteolytic digestion of fraction BM(1) liberated free xanthine oxidase from the fat-globule membrane with a corresponding alteration in X/N value.

SUBMITTER: Briley MS

PROVIDER: S-EPMC1168363 | biostudies-other | 1974 Oct

REPOSITORIES: biostudies-other

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Association of xanthine oxidase with the bovine milk-fat-globule membrane. Nature of the enzyme-membrane association.

Project description:1. Xanthine oxidase (EC 1.2.3.2) was found to represent more than 8% of the intrinsic protein of the bovine milk-fat-globule membranes. 2. Less than 25% of the xanthine oxidase activity of the fat-globule membrane was solubilized with 0.1 M-sodium pyrophosphate buffer or 2M-NaCl. Of the particulate activity remaining 56% was solubilized with Triton X-100. 3. The xanthine oxidase activity solubilized with buffer, 2M-NaCl or Triton X-100 was not liberated as the free enzyme. Only tryptic digestion was found to release the free enzyme from the fat-globule membrane. Tryptic digestion also liberated free xanthine oxidase from those fractions solubilized by buffer or NaCl, but not from those fractions solubilized with Triton X-100 or by sonication. 4. The effect of membrane association on the catalytic properties of the enzyme could be mimicked by low pH or by the presence in the assay mixture of certain concentrations of 2-methyl-propan-2-ol, but not 1,4-dioxan, suggesting that hydrogen-bonding rather than low dielectric constant may be involved. 5. The origin of the milk-fat-globule membrane is discussed with reference to the intrinsic nature of the associated xanthine oxidase activity.

| S-EPMC1165467 | biostudies-other

Preparation of monoclonal antibodies to xanthine oxidase and other proteins of bovine milk-fat-globule membrane.

Project description:Nine hybridomas secreting monoclonal antibody to proteins of bovine milk-fat-globule membrane were isolated. All nine cell lines continued to secrete monoclonal antibody after serial transfer in culture and after passage as solid tumours in Balb/cJ mice. Four of the cell lines secreted monoclonal antibody specific for xanthine oxidase, one of the major proteins of milk-fat-globule membrane.

| S-EPMC1161979 | biostudies-other

Xanthine Oxidoreductase mediates milk fat globule secretion.

Project description:Analysis of the milk fat globule proteome from mice with a mammary-specific knockout of Xanthine Oxidoreductase.

2017-05-31 | PXD003336 | Pride

Crystal structures of bovine milk xanthine dehydrogenase and xanthine oxidase: structure-based mechanism of conversion.

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| S-EPMC1135677 | biostudies-other

Isolation and structural characterization of alkali-labile oligosaccharides from bovine milk-fat-globule membrane.

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| S-EPMC1183999 | biostudies-other

Role of milk fat globule membrane (MFGM) in modulating gene expression in humans

Project description:The aim of this study was to investigate if milk fat globule membrane (MFGM) enclosing the dairy fat influence peripheral blood mononuclear cells (PBMC) gene expression. This study was a 8-week single-blind, randomized, controlled isocaloric trial with two parallel groups including overweight (mean BMI: 28) adult women (n=30). All subjects consumed 40 g dairy fat per day either as cream (MFGM diet) or as butter oil (control diet). MFGM diet and control diet showed differential responses in plasma cholesterol. Absolute differences in gene expression were calculated for each gene in each subject, comparing after with before the intervention. These absolute differences in gene expression were compared between intervention groups with T-test and with Significance Analysis of Microarrays (SAM). 19 genes were significantly different regulated by the two diets with a FDR of 23%. Most of thechanges in gene expression correlated with changes in blood lipids. Patients were examined in the morning after 12 h's fasting. Whole blood was obtained before (W0) and after completion (W8) of the dietary intervention for isolation of PBMCs and RNA extraction. From total RNA we prepared and hybridised biotinylated complementary RNA to GeneChip Human Gene 1.1 ST Arrays (Affymetrix Inc., Santa Clara, CA), and then washed, stained and scanned the slides using standardised protocols (Affymetrix Inc.). Signicance analysis of microarrays (SAM) was use to compare the difference in gene expression between groups.

2015-08-01 | E-GEOD-60148 | biostudies-arrayexpress

Quantitative Label-Free Proteomic Analysis of Milk Fat Globule Membrane in Donkey and Human Milk.

Project description:Previous studies have found donkey milk (DM) has the similar compositions with human milk (HM) and could be used as a potential hypoallergenic replacement diet for babies suffering from cow's milk allergy. Milk fat globule membrane (MFGM) proteins are involved in many biological functions, behaving as important indicators of the nutritional quality of milk. In this study, we used label-free proteomics to quantify the differentially expressed MFGM proteins (DEP) between DM (in 4-5 months of lactation) and HM (in 6-8 months of lactation). In total, 293 DEP were found in these two groups. Gene Ontology (GO) enrichment analysis revealed that the majority of DEP participated in regulation of immune system process, membrane invagination and lymphocyte activation. Several significant Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were determined for the DEP, such as lysosome, galactose metabolism and peroxisome proliferator-activated receptor (PPAR) signaling pathway. Our study may provide valuable information in the composition of MFGM proteins in DM and HM, and expand our knowledge of different biological functions between DM and HM.

| S-EPMC8258387 | biostudies-literature

Healthy Breastfeeding Infants Consume Different Quantities of Milk Fat Globule Membrane Lipids.

Project description:The human milk fat globule membrane (MFGM) contains important lipids for growing infants. Anthropometric measurements, milk samples, and infant milk intake were collected in a cohort of eleven healthy mother-infant dyads during exclusive breastfeeding from birth to six months. One hundred and sixty-six MFGM lipids were analysed using liquid chromatography-mass spectrometry, and the infant intake was calculated. The concentrations and intake were compared and associations between infant intake and growth characteristics explored. The lipid concentrations and infant intake varied widely between mother-infant dyads and between months one and three. The infant intake for many species displayed positive correlations with infant growth, particularly phospholipid species. The high variation in lipid intake is likely an important factor in infant growth, with strong correlations identified between the intake of many MFGM lipids and infant head circumference and weight. This study highlights the need for intake measurements and inclusion in cohort studies to elucidate the role of the human milk lipidome in infant growth and development.

| S-EPMC8471100 | biostudies-literature

Milk Fat Globule Membrane Supplementation in Children: Systematic Review with Meta-Analysis.

Project description:(1) Background: Milk fat globule membrane (MFGM), composing fat droplets responsible for lipid transport in breast milk, has been shown to possess immunological and antimicrobial effects. Standard formulas (SF) are devoid of MFGMs during the production process. The study's aim was to evaluate the safety and benefits of MFGMs supplementation in children. (2) Methods: We searched four databases for randomized controlled trials evaluating the supplementation of MFGMs in children. Growth parameters were chosen as the primary outcome. (3) Results: Twenty-four publications of seventeen studies were included. Meta-analyses assessing the primary outcomes at the age of 4 months included four studies (814 children) comparing the MFGM-supplemented formulas and SF, and two trials (549 children) comparing the MFGM-supplemented formulas and breastfeeding. The primary outcomes were non-inferior in all the experimental MFGM formulas compared to SF, or even represented more similar results to breastfed infants. The promising effects, including a lower incidence of acute otitis media and improved cognitive development, cannot be firmly confirmed due to the small amount of existing evidence. No significant adverse effects were reported in any of the assessed products. (4) Conclusions: The available data signaled beneficial effects and a good safety profile, requiring future research with well-designed trials.

| S-EPMC7996302 | biostudies-literature

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