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Dallas DC, Martin WF, Strum JS, Zivkovic AM, Smilowitz JT, Underwood MA, Affolter M, Lebrilla CB, German JB. N-linked glycan profiling of mature human milk by high-performance microfluidic chip liquid chromatography time-of-flight tandem mass spectrometry. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2011; 59:4255-63. [PMID: 21384928 PMCID: PMC4422756 DOI: 10.1021/jf104681p] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
N-Linked glycans of skim human milk proteins were determined for three mothers. N-Linked glycans are linked to immune defense, cell growth, and cell-cell adhesion, but their functions in human milk are undetermined. Protein-bound N-linked glycans were released with peptidyl N-glycosidase F (PNGase F), enriched by graphitized carbon chromatography, and analyzed with Chip-TOF MS. To be defined as N-glycans, compounds were required, in all three procedural replicates, to match, within 6 ppm, against a theoretical human N-glycan library and be at least 2-fold higher in abundance in PNGase F-treated than in control samples. Fifty-two N-linked glycan compositions were identified, and 24 were confirmed via tandem mass spectra analysis. Twenty-seven compositions have been found previously in human milk, and 25 are novel compositions. By abundance, 84% of N-glycans were fucosylated and 47% were sialylated. The majority (70%) of total N-glycan abundance was composed of N-glycans found in all three milk samples.
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Affiliation(s)
- David C. Dallas
- Department of Food Science, University of California at Davis, One Shields Avenue, Davis, CA, 95616, USA
- Foods for Health Institute, University of California at Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - William F. Martin
- Department of Food Science, University of California at Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - John S. Strum
- Department of Chemistry, University of California at Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Angela M. Zivkovic
- Department of Food Science, University of California at Davis, One Shields Avenue, Davis, CA, 95616, USA
- Foods for Health Institute, University of California at Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Jennifer T. Smilowitz
- Department of Food Science, University of California at Davis, One Shields Avenue, Davis, CA, 95616, USA
- Foods for Health Institute, University of California at Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Mark A. Underwood
- Foods for Health Institute, University of California at Davis, One Shields Avenue, Davis, CA, 95616, USA
- Department of Pediatrics, University of California Davis, 2315 Stockton Blvd., Sacramento, CA, 95817, USA
| | - Michael Affolter
- Nestlé Research Center, Vers-chez-les-Blanc, CH-1000 Lausanne 26, Switzerland
| | - Carlito B. Lebrilla
- Foods for Health Institute, University of California at Davis, One Shields Avenue, Davis, CA, 95616, USA
- Department of Chemistry, University of California at Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - J. Bruce German
- Department of Food Science, University of California at Davis, One Shields Avenue, Davis, CA, 95616, USA
- Foods for Health Institute, University of California at Davis, One Shields Avenue, Davis, CA, 95616, USA
- Nestlé Research Center, Vers-chez-les-Blanc, CH-1000 Lausanne 26, Switzerland
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Abstract
The rapid growth of infant brains places an exceptionally high demand on the supply of nutrients from the diet, particularly for preterm infants. Sialic acid (Sia) is an essential component of brain gangliosides and the polysialic acid (polySia) chains that modify neural cell adhesion molecules (NCAM). Sia levels are high in human breast milk, predominately as N-acetylneuraminic acid (Neu5Ac). In contrast, infant formulas contain a low level of Sia consisting of both Neu5Ac and N-glycolylneuraminic acid (Neu5Gc). Neu5Gc is implicated in some human inflammatory diseases. Brain gangliosides and polysialylated NCAM play crucial roles in cell-to-cell interactions, neuronal outgrowth, modifying synaptic connectivity, and memory formation. In piglets, a diet rich in Sia increases the level of brain Sia and the expression of two learning-related genes and enhances learning and memory. The purpose of this review is to summarize the evidence showing the importance of dietary Sia as an essential nutrient for brain development and cognition.
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Affiliation(s)
- Bing Wang
- Human Nutrition Unit, School of Molecular and Microbial Biosciences, University of Sydney, Australia and School of Medicine, Xiamen University, P. R. China.
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Chiarini A, Fiorilli A, Siniscalco C, Tettamanti G, Venerando B. Solubilization of the membrane-bound sialidase from pig brain by treatment with bacterial phosphatidylinositol phospholipase C. J Neurochem 1990; 55:1576-84. [PMID: 2213010 DOI: 10.1111/j.1471-4159.1990.tb04941.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The total pellet from pig forebrain (from which the cytosolic sialidase was completely washed out) was treated with phosphatidylinositol phospholipase C (PIPLC) and centrifuged at high speed. The supernatant contained sialidase and 5'-nucleotidase activities. The greatest liberation of sialidase was obtained after incubation for 20 min with PIPLC at 37 degrees C using pH 6.0 and a ratio between PIPLC (as units) and protein of 1.6. Under these conditions, the release of sialidase, 5'-nucleotidase, and protein was 22, 50, and 18.5%, respectively. On treatment with PIPLC, a purified preparation of pig brain neuronal (synaptosomal) membranes released 28% of its sialidase whereas a purified preparation of pig brain lysosomes did not liberate any sialidase activity. The pH optimum of sialidase present in the supernatant obtained after PIPLC treatment of the total pellet was 4.2, the same as that of the enzyme embedded in the membrane. When this supernatant was subjected to ammonium sulfate fractionation, 88% of its sialidase, having a pH optimum of 4.2, was recovered in the fraction precipitated between 20 and 45% of salt saturation and subsequently dialyzed. Ammonium sulfate treatment caused the appearance of a second sialidase activity, having a pH optimum of 6.6 and behaving on fractionation similarly to the pH 4.2 sialidase. The Km and Vmax values of pH 4.2 and pH 6.6 sialidase were similar (1.48 x 10(-4) and 0.98 x 10(-4) M for Km and 1.6 and 1.4 mU/mg of protein for Vmax, respectively), whereas the stability on standing at 4 degrees C or exposure to freezing and thawing cycles was greater for pH 4.2 sialidase.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- A Chiarini
- Department of Medical Chemistry and Biochemistry, Medical School, University of Milan, Italy
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Abstract
A synaptosome-enriched fraction from sheep cortex was incubated with L-fucose. The uptake of the sugar into this preparation was dependent on time, temperature, and concentration. A Kmapp of 0.94 mM-L-fucose and a Vmaxapp value of 0.24 nM-L-fucose/mg synaptosomal soluble protein/20 min was determined. After incubation for 10 min at 25 degrees C with L-[3H]fucose, 70% of the radioactive label was found in the soluble fraction. DEAE-cellulose chromatography resulted in the elution of three fucosylprotein peaks which were then characterised by gel filtration and sodium dodecyl sulfate-polyacrylamide electrophoresis (SDS-PAGE). At least eleven 3H protein-staining bands were identified with M. W. 13,000--115,000. Control experiments involving the incubation of the hexose with heat-treated synaptosomes and myelin, mitochondria, and microsomes indicted that the tritiated material associated with the synaptosomal soluble fraction was not due to nonspecific binding or to the presence of contaminating subcellular material. A 3H glycopeptide was identified, and on analysis the carbohydrate moiety was found to be rich in sialic acid, fucose, galactose, mannose, and N-acetylglucosamine. Mild acid treatment of the glycopeptide released fucose, which implies that this carbohydrate occupies a terminal position in the oligosaccharide chain. From these results it is proposed that synthesis or the modification of soluble fucosylglycoproteins is possible in synaptosomes.
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Abstract
Synaptosomes from sheep brain were incubated with Na2(35)SO4. After lysis at least twelve 35S-containing proteins were identified in the synaptosomal soluble fraction with molecular weights ranging between 13,000 and 150,000. Extraction of the particulate fraction with SDS/urea revealed a further eight [35S]proteins with 27,000-140,000 molecular weights. A glycopeptide rich in fucose, sialic acid, N-acetylglucosamine and galactose was isolated from papain treated synaptosomal material. Over half of the hexosamine and neutral sugar residues were found to contain 35S. These findings suggest that sulphation of glycoproteins can occur in isolated nerve terminals.
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