Protein glycosylation can play an important role in the biological activity, stability, biological half-life and immunogenicity of biological drugs. Glycosylation is a post-translational modification. Unlike transcription, it is a non-template-driven enzymatic modification process. Therefore, glycosylation can vary with production conditions. The characterization of glycosylation is necessary to understand the structure-activity relationship. For example, removal of core fucose from the N-glycans on the heavy chain of IgG1 can significantly enhance the binding affinity of FcγRIIIa, thereby increasing the cytotoxic activity of antibody-dependent cells. Many biopharmaceuticals are produced in non-human cell lines, which may increase glycosylation of non-human types (for example, Galα1-3Gal or Neu5Gc). This may give rise to changed immunogenicity that leading to clinical consequences such as reduced efficacy, changes in pharmacokinetics, general immune and hypersensitivity reactions, and drug neutralization. Therefore, it is important to combine glycan structure analysis, functional testing, clinical data and prior knowledge to determine the Glycosylation Key Quality Attributes (GCQAs). Knowledge of GCQA will improve product efficacy and reduce the risk of adverse reactions. Due to the importance of glycosylation for drug efficacy and safety, regulatory guidelines require glycan analysis for IND submissions (for example, ICH guideline Q6B: Part 6.11(f)).
Fig.1 Glycan Analytical Methods
Note: 1Enzymatic release is more specific than chemical release, and chemical release 2can lead to some degradation of the glycan.
Fig.2 How to select a glycan label.
Figure 3 provides a schematic diagram of these strategies used in MS-based glycoprotein analysis.
The choice of MS analysis strategy for protein glycosylation structure characterization depends on the level of structural information required. The complete protein analysis (Method 2) is very simple, not only can provide information about the quality of glycans, but also determine the molecular weight of the protein. Although this method provides an estimate of the quality of glycans, the molecular weight distribution map provided from the released glycans (Method 1) is a more accurate measurement. When Method 1 is used in combination with tandem MS, this analysis can be used to confirm the composition of the observed mass (ie the correct combination of glycan constructs). However, this method requires more sample size and additional time and operation. When there is more than one glycosylation site in the protein or protein sequence information is needed in addition to identifying the glycan structure, glycopeptide analysis (Method 3) is most advantageous. Using this method, glycan structure, glycan attachment site and protein sequence information can be obtained in a single experiment. In the case that a protein with a single glycosylation site requires glycan information, methods 1 and 2 are more appropriate, but when there are multiple glycosylation sites, method 3 can be used to provide site-specific information, although sometimes Data analysis can be challenging. This information is particularly useful for understanding structure-function relationships.
Figure 3: Workflow for MS-based glycoprotein analysis.
With extensive experience in glycan characterization, our team can work on custom solutions to meet the unique requirements of each product. With flexible global capabilities, you can provide services where you need it most.
Contact our expert scientists today to discuss how our range of glycan analytical services can improve your unique process.
Creative Biolabs provides luciferase-based ADCC assay. This Jurkat cell based assay is pioneered by Creative Biolabs, and the methodology is very well accepted by the field. See attached ADCC Reporter Assay Protocol for further details.
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