O-linked glycans are a common covalent modification of serine and threonine residues of mammalian glycoproteins.

The most common type of O-linked glycans found on secreted mammalian glycoproteins and mucins (proteins conjugated to carbohydrate) is from the addition of N-acytylgalactosamine (GalNac) to serine or threonine residues.

The Core 1 structure is generated by the addition of galactose b1-3 to this GalNAc. The Core 2 structure is generated by the further addition of N-acetyl-glucosamine b1-6 to the N-acetyl-galactosamine on the Core 1 structure.

In total eight different O-linked glycans core structures have been identified and all of these can be further elongated by the addition of a number of monosaccharides including sialic acids.

O-glycans are present in biopharmaceuticals such as erythropoeitin (EPO), Etanercept (Enbrel) and human Factor VIII (FVIII).Core 1 and Core 2 O-glycans are also present in biopharmaceuticals such as erythropoeitin (EPO), Etanercept (Enbrel), humanFactor VIII(FVIII), Factor IX and insulin glargine.

The Ludger standards have a purity of >90% as assessed by HILIC-HPLC and can be used as internal references or system suitability standards for peak assignment during HPLC or UPLC analysis.

Core 1 – Galactose-ß-(1-3)-GalNAc
Sialylated Core 1 – monosialylated core 1 O-glycan
Disialylated Core 1 – disialylated core 1 O-glycan
Disialylated Core 2 – disialylated core 2 glycan