2. Academic Validation
  3. O-linked glycosylations in human milk casein and major whey proteins during lactation

O-linked glycosylations in human milk casein and major whey proteins during lactation

  • Int J Biol Macromol. 2024 May;267(Pt 2):131613. doi: 10.1016/j.ijbiomac.2024.131613.
Martin Nørmark Thesbjerg 1,  Katrine Overgaard Poulsen 2,  Julie Astono 3,  Nina Aagaard Poulsen 3,  Lotte Bach Larsen 3,  Søren Drud-Heydary Nielsen 3,  Allan Stensballe 4,  Ulrik Kræmer Sundekilde 3
Affiliations

Affiliations

  • 1 Department of Food Science, Aarhus University, Agro Food Park 48, DK-8200 Aarhus N, Denmark; Sino-Danish College (SDC), University of Chinese Academy of Science, Huairou District, Beijing 101408, China. Electronic address: mnt@food.au.dk.
  • 2 Department of Food Science, Aarhus University, Agro Food Park 48, DK-8200 Aarhus N, Denmark; Sino-Danish College (SDC), University of Chinese Academy of Science, Huairou District, Beijing 101408, China.
  • 3 Department of Food Science, Aarhus University, Agro Food Park 48, DK-8200 Aarhus N, Denmark.
  • 4 Department of Health Science and Technology, Aalborg University, Selma Lagerløfsvej 249, DK-9260 Gistrup, Denmark; Clinical cancer center, Aalborg University Hospital, 9000 Aalborg, Denmark.
PMID: 38642686 DOI: 10.1016/j.ijbiomac.2024.131613
Abstract

As glycosylations are difficult to analyze, their roles and effects are poorly understood. Glycosylations in human milk (HM) differ across lactation. Glycosylations can be involved in antimicrobial activities and may serve as food for beneficial Microorganisms. This study aimed to identify and analyze O-linked glycans in HM by high-throughput mass spectrometry. 184 longitudinal HM samples from 66 donors from day 3 and months 1, 2, and 3 postpartum were subjected to a post-translational modification specific enrichment-based strategy using TiO2 and ZrO2 beads for O-linked Glycopeptide enrichment. β-CN was found to be a major O-linked glycoprotein, additionally, αS1-CN, κ-CN, lactotransferrin, and albumin also contained O-linked glycans. As glycosyltransferases and glycosidases are involved in assembling the glycans including O-linked glycosylations, these were further investigated. Some glycosyltransferases and glycosidases were found to be significantly decreasing through lactation, including two O-linked glycan initiator Enzymes (GLNT1 and GLNT2). Despite their decrease, the overall level of O-linked glycans remained stable in HM over lactation. Three different motifs for O-linked glycosylation were enriched in HM proteins: Gly-Xxx-Xxx-Gly-Ser/Thr, Arg-Ser/Thr and Lys-Ser/Thr. Further O-linked glycan motifs on β-CN were observed to differ between intact proteins and endogenous Peptides in HM.

Keywords

Casein; Human milk; O-linked glycosylation; Whey protein; β-CN.

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