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

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 LysSer/Thr. Further O-linked glycan motifs on β-CN were observed to differ between intact proteins and endogenous peptides in HM.PMID:38642686 | DOI:10.1016/j.ijbiomac.2024.131613

Source: International Journal of Biological Macromolecules - April 20, 2024 Category: Biochemistry Authors: Martin N ørmark Thesbjerg Katrine Overgaard Poulsen Julie Astono Nina Aagaard Poulsen Lotte Bach Larsen S øren Drud-Heydary Nielsen Allan Stensballe Ulrik Kr æmer Sundekilde Source Type: research