Comparative Glycomics of Fat Globule Membrane Glycoconjugates from Buffalo (Bubalus bubalis) Milk and Colostrum

Proteomic and phosphoproteomic reveal immune-related function of milk fat globule membrane in bovine milk of different lactation periods

Information regarding protein expression and phosphorylation modifications in the bovine milk fat globule membrane is scarce, particularly throughout various lactation periods. This study employed a complete proteome and phosphoproteome between bovine colostrum and mature milk. A total of 11 proteins were seen in both protein expression and phosphorylation levels. There were 400 proteins identified in only protein expression, and 104 phosphoproteins identified in only phosphorylation levels. A total of 232 significant protein characteristics were identified within the proteome and significant phosphorylation sites within 86 phosphoproteins of the phosphoproteome. Biological activities and pathways primarily exhibited associations with the immune system. Simultaneously, a comprehensive analysis of proteins and phosphorylation sites using a multi-omics approach. Hence, the data we have obtained has the potential to expand our understanding of how the bovine milk fat globule membrane might be utilized as a beneficial component in dairy products.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2017-2018

This review is the tenth update of the original article published in 1999 on the application of matrix-assisted laser desorption/ionization mass spectrometry (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2018. Also included are papers that describe methods appropriate to glycan and glycoprotein analysis by MALDI, such as sample preparation techniques, even though the ionization method is not MALDI. Topics covered in the first part of the review include general aspects such as theory of the MALDI process, new methods, matrices, derivatization, MALDI imaging, fragmentation and the use of arrays. The second part of the review is devoted to applications to various structural types such as oligo- and poly-saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Most of the applications are presented in tabular form. The third part of the review covers medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. The reported work shows increasing use of combined new techniques such as ion mobility and highlights the impact that MALDI imaging is having across a range of diciplines. MALDI is still an ideal technique for carbohydrate analysis and advancements in the technique and the range of applications continue steady progress.

Functional Significance of Different Milk Constituents in Modulating the Gut Microbiome and Infant Health

Human milk, the gold standard for optimal nourishment, controls the microbial composition of infants by either enhancing or limiting bacterial growth. The milk fat globule membrane has gained interest in gut-related functions and cognitive development. The membrane proteins can directly interact with probiotic bacteria, influencing their survival and adhesion through gastrointestinal transit, whereas membrane phospholipids increase the residence time of probiotic bacteria in the gut. The commensal bacteria in milk act as the initial inoculum in building up the gut colonization of an infant, whereas oligosaccharides promote proliferation of beneficial microorganisms. Interestingly, milk extracellular vesicles are also involved in influencing the microbiota composition but are not well-explored. This review highlights the contribution of different milk components in modulating the infant gut microbiota, particularly the fat globule membrane, and the complex interplay between host- and brain-gut microbiota signaling affecting infant and adult health positively.

Detailed Characterization of Antipathogenic Properties of Human Milk N-Glycome, against Staphylococcus aureus, Indicating Its Targeting on Cell Surface Proteins

Human milk N-glycome was previously identified to have strong antipathogenic activities. This study is aimed to characterize the detailed antibacterial properties and the potential function mechanism of human milk N-glycome against Staphylococcus aureus. A serials of traditional antibacterial assays showed that human milk N-glycome possessed both bacteriostatic and bactericidal activities, which was further confirmed by the cell structure disruption including the change of transmembrane potential and leakage of intracellular contents. The results of the bacterial surface zeta potential and hydrophobicity, bacterial binding assay, gel shift assay, and fluorescence spectra and the different synergistic effects of human milk N-glycome combined with different antibiotics indicated that the bacterial surface proteins could be the targets of human milk N-glycome. Moreover, human milk N-glycome also showed antibiofilm activity. In conclusion, human milk N-glycome exhibited good potential for acting as an antibacterial substance against S. aureus and the antibacterial mechanism was a cell surface targeting action.

Mass spectrometry-based qualitative and quantitative N-glycomics: An update of 2017-2018

N-glycosylation is one of the most frequently occurring protein post-translational modifications (PTMs) with broad cellular, physiological and pathological relevance. Mass spectrometry-based N-glycomics has become the state-of-the-art instrumental analytical pipeline for sensitive, high-throughput and comprehensive characterization of N-glycans and N-glycomes. Improvement and new development of methods in N-glycan release, enrichment, derivatization, isotopic labeling, separation, ionization, MS, tandem MS and informatics accompany side-by-side wider and deeper application. This review provides a comprehensive update of mass spectrometry-based qualitative and quantitative N-glycomics in the years of 2017-2018.

Characterization and comparison of milk fat globule membrane N-glycoproteomes from human and bovine colostrum and mature milk

Human and bovine milk fat globule membrane (MFGM) proteins have been identified and characterized; however, their glycosylation during lactation remains unclear. We adopted a glycoproteomics approach to profile and compare MFGM N-glycoproteomes in human and bovine milk during lactation. A total of 843, 718, 614, and 273 N-glycosite peptides corresponding to 465, 423, 334, and 176 glycoproteins were identified in human colostrum, human mature milk, bovine colostrum, and bovine mature milk, respectively. The biological functions of these MFGM N-glycoproteins were revealed through bioinformatics. Substantial differences were observed between human and bovine milk, and immune-related MFGM N-glycoproteins varied between colostrum and mature milk from both species. Our results expand current knowledge of MFGM N-glycoproteomes, and further demonstrate the complexity and biological functions of MFGM N-glycosylation. These data can provide references for the application of bovine MFGM N-glycoproteins in infant formula to resemble human milk and in functional foods.

Comparative Site-Specific N-Glycosylation Analysis of Lactoperoxidase from Buffalo and Goat Milk Using RP-UHPLC-MS/MS Reveals a Distinct Glycan Pattern

The N-glycan pattern of lactoperoxidase (LPO) from buffalo and goat milk was analyzed with the corresponding site of attachment. The enzyme was purified from whey on cation exchange chromatography, proteolyzed using chymotrypsin, and the resulting (glyco)peptides were directly analyzed on reverse phase ultrahigh performance liquid chromatography coupled to ESI-Q-TOF MS in tandem mode. N-Glycans such as high mannose, complex, and hybrid types were identified in buffalo and goat LPO. Among sialylated complex and hybrid types, the terminal Neu5Ac linked to either LacNAc/LacdiNAc found exclusively in buffalo, whereas Neu5Gc linked to LacdiNAc was predominant in goat LPO. N-Glycans at Asn₆ and Asn₃₄₉ in buffalo LPO were completely core fucosylated, while these sites in goat LPO showed differential fucosylation. Differential occupancy was observed at Asn₁₁₂ with or without nonfucosylated complex and hybrid types, whereas mainly high mannose glycans were found in Asn₂₂₂ in both of the LPOs. The presence of glycan isomers in buffalo and goat LPO was also observed. Despite the presence of distinct complex and hybrid glycans, the common glycosylation features in buffalo and goat LPO were identified and are comparable with those of bovine LPO. This finding could be useful in exploring the beneficial role of these glycans as functional ingredients for food products.

An Efficient Glycoblotting-Based Analysis of Oxidized Lipids in Liposomes and a Lipoprotein

Although widely occurring lipid oxidation, which is triggered by reactive oxygen species (ROS), produces a variety of oxidized lipids, practical methods to efficiently analyze oxidized lipids remain elusive. Herein, it is shown that the glycoblotting platform can be used to analyze oxidized lipids. Analysis is based on the principle that lipid aldehydes, one of the oxidized lipid species, can be captured selectively, enriched, and detected. Moreover, 3-methyl-1-p-tolyltriazene (MTT) methylates phosphoric and carboxylic acids, and this MTT-mediated methylation is, in combination with conventional tandem mass spectrometry (MS/MS) analysis, an effective method for the structural analysis of oxidized lipids. By using three classes of standards, liposomes, and a lipoprotein, it is demonstrated that glycoblotting represents a powerful approach for focused lipidomics, even in complex macromolecules.