Therapeutic Glycoproteins and Polysaccharide Vaccines Laboratory

Glycobiology and Therapeutic Glycoproteins

Glycoproteins are the active ingredients in most biologic products. At the Centre for Vaccine Evaluation, our glycobiology and glycoprotein research helps provide new information and tools for studying biologics.

 

Why We Study Glycoproteins

Most biological therapeutics are glycoproteins, that is, proteins with carbohydrates attached to them. These carbohydrate “sugar chains” attach to the protein at specific sites and are known as glycans. Glycans range in size from single monosaccharides (simple sugars) to larger oligosaccharides built up from monosaccharides. They differ from one another greatly, depending on many factors.

This heterogeneity leads to different glycoforms of the same protein. Each glycoform potentially possesses different biophysical properties and biological activities. Different glycoforms may also be used as markers of certain physiological and disease states.

Glycosylation of a glycoprotein may affect:

  • Protein folding and final molecular structure;
  • Solubility, stability, resistance to degradation;
  • Transport (inside/outside cell), bio-distribution;
  • Clearance rate / circulation time;
  • Immunogenicity, antigenicity;
  • Specific activity.

 

How We Study Glycobiology and Therapeutic Glycoproteins

In our laboratory, at the Centre for Vaccine Evaluation, we tackle questions regarding the glycosylation of therapeutic glycoproteins. We apply our expertise to provide new knowledge and tools that help us analyse therapeutic glycoprotein efficacy and safety. With our research, we help:

  • Characterize the glycans attached to a given glycoprotein;
  • Understand the relationships between the glycoform profile and function for a given glycoprotein;
  • Assess glycoprotein efficacies based on their glycoform profiles;
  • Monitor and compare different batches/lots of the same or similar glycoproteins;
  • Examine methods that may let us control glycan patterns or heterogeneity during production.

 

Concepts and Tools We Use to Study Glycobiology and Therapeutic Glycoproteins

Glycans are polymers of monosaccharides. In mammals, they range in size from a single monosaccharide to oligosaccharides containing more than 20 monosaccharide units. The monosaccharides commonly found in mammalian glycoproteins are the six neutral sugars, plus the family of negatively charged sialic acids.

Monosaccharides in glycans connect to each other through glycosidic bonds between the anomeric or reducing hydroxyl (OH) group on one monosaccharide unit and a hydroxyl group on another monosaccharide. There is an enormous potential for structural diversity in oligosaccharides, which arises from the following:

  • Identity and sequence of constituent monosaccharides;
  • Anomeric configuration of glycosidic bonds (alpha, α or beta, β);
  • Linkage positions of the glycosidic bonds (which hydroxyl groups);
  • Type and degree of glycan branching (number of “antennae”).

Glycosylation is the most common modification made to proteins after they are synthesized in the cell, and about 70% of proteins are glycoproteins. The two most common ways in which glycans attach to proteins are through N-linked and O-linked glycosylation.

Separation and analysis of glycans removed from glycoproteins are often performed by various chromatographic methods such as high-pH anion-exchange (HPAE) and high-performance or high-pressure liquid chromatography (HPLC). Native or chemically modified glycans can be detected by electrochemical and fluorescence methods.

 

Research Highlight 1: Antibody Glycosylation and Implications for Antibody Function

Antibodies are widely used in the diagnosis, imaging, and therapy of a broad variety of different illnesses. They are glycoproteins with glycans attached at a specific, fully conserved amino acid.

Their glycosylation state strongly affects their structure and function, and therefore their efficacy and safety. In our laboratory, we are conducting glyco-analytical surveys of representative commercially available monoclonal antibodies and other immunoglobulin products.

We are working to:

  • Better appreciate the variation within and between different immunoglobulin products. We want to understand how these variations have implications for functional differences between them. Eventually, we will expand the glycosylation survey to include comparisons between other therapeutic glycoproteins including antibody related products, hormones, enzymes, and other biologicals.

 

Research Highlight 2: Glycoanalysis of Meningococcal Vaccines

Many vaccines against bacterial infection consist of purified polysaccharides derived from the bacterial capsules of the target species and strains. The efficacy and safety of these vaccines depend on the identity, purity and amount of each polysaccharide component.

The active components of most meningococcal vaccines against Neisseria meningitidis are polysaccharides representing up to four serotypes named ACYW that are derived from the bacterial capsule of different strains.

We are working to:

  • Develop techniques to analyze and quantitate the polysaccharide components of meningococcal vaccines. These are essential for evaluation of their efficacy and safety.

 


For information about the lead scientist of this laboratory, please visit their  Directory of Scientists and Professionals profile.

Date modified: