Quantitative analysis of bovine whey glycoproteins using the overall N-linked whey glycoprofile

Rivca L Valk-Weeber,Talitha Eshuis-De Ruiter,Lubbert Dijkhuizen,Sander S Van Leeuwen

doi:10.1016/j.idairyj.2020.104814

Rivca L Valk-Weeber, Talitha Eshuis-De Ruiter + Show 2 more

Open Access

https://doi.org/10.1016/j.idairyj.2020.104814

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Abstract

Bovine whey is an important ingredient in human nutrition and contains many biofunctional, glycosylated proteins. Knowledge on the glycoprotein composition of whey and whey products is valuable for the dairy industry. This paper describes a method for the characterisation of whey, or whey powders, by N-linked glycoprofile analysis. Application of the method for analysis of whey protein products showed clear differences in glycoprotein composition between concentrate, isolate and demineralised whey powders. The quantitative potential was explored by screening 100 pooled farm milk samples. IgG and lactoferrin protein concentrations determined by N-glycoprofile analysis matched well with ELISA results. The protein concentration of GlyCAM-1 was determined to be ≥1 mg mL−1. The approaches presented in this work allow simultaneous concentration estimation of the three major whey glycoproteins, lactoferrin, IgG and GlyCAM-1 on the basis of their N-linked glycoprofiles, also in highly processed samples where conventional methods of detection (ELISA) are less suitable.

Highlights

Bovine milk is a complex mixture of water, lipids, carbohydrates, vitamins, minerals and proteins, which can be further divided into caseins and whey proteins (Korhonen, 2009)
Anonymised powders of whey protein concentrate (WPC), whey protein isolate (WPI) and demineralised whey products with different processing backgrounds were obtained from FrieslandCampina Domo
It is possible that this method underestimated the GlyCAM-1 concentration. These results show that GlyCAM-1 glycans dominate the glycoprofile of bovine whey, and that its protein concentration may be much higher than previously reported

Summary

Introduction

Bovine milk is a complex mixture of water, lipids, carbohydrates (e.g., lactose), vitamins, minerals and proteins, which can be further divided into caseins and whey proteins (Korhonen, 2009). N-linked glycans can be further divided into three main classes, oligomannose, hybrid- or complex-type, depending on the monosaccharide composition of the glycan antennae present on the common core structure of two N-acetylglucosamine and three mannoses (GlcNAc2Man3) (Moremen, Tiemeyer, & Nairn, 2012). Some proteins, such as lactoferrin, are exclusively N-glycosylated, while the casein fragment casein glycomacropeptide (GMP) is exclusively Oglycosylated (Moore, Anderson, Groom, Haridas, & Baker, 1997; Vreeman, Visser, Slangen, & Van Riel, 1986). The protein GlyCAM-1 carries both N- and O-linked glycans (Kjeldsen, Haselmann, Budnik, Sørensen, & Zubarev, 2003)

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