Custom Neoglycoprotein Service
We are able to link a wide range of carbohydrates to proteins and offer a custom service that can be tailored to meet clients’ specific requirements. We have made a diverse range of neoglycoproteins from simple monosaccharides to complex plant derived oligosaccharides and carbohydrate tumour antigens. Our neoglycoproteins are frequently used as the solid phase in ELISA assays and we can provide experimental details in this application if required. We can also manufacture our existing range of neoglycoproteins on a larger scale. Our present methods of choice link carbohydrates via the anomeric position to the ε-amino groups of lysine residues or to sulphydryl groups and we offer a range of linker arms.
• The most commonly used short linker is 3-atoms and sometimes is the choice for antigen presentation, whilst the most commonly used long linker is 14-atoms, frequently preferred as an enzyme acceptor. Other linker arms are possible and are available on request.
• We aim to link at least 8 carbohydrate residues per protein molecule if the target amino acid is lysine.
• As a general rule, the coupling ratio decreases with increasing molecular weight of carbohydrate due to a combination of poorer reactivity and increasing steric hindrance.
• If the target group is sulfydryl, then all free SH groups on the protein are usually reacted. We can discuss other coupling options, depending on specific applications.
In terms of protein the vast majority of requests are for BSA, HSA or other species’ serum albumins. We can use other proteins depending on their amenability to analysis and the availability of reactive groups.
There are some restrictions that apply to the present techniques:
• The link between carbohydrate and protein is generally β, however α linkeage may be possible.
• A number of carbohydrates, such as oligosaccharides with a fucose proximal to the anomeric residue may only react poorly.
• Our present minimum scale will yield 5 mg of neoglycoprotein.
All of our neoglycoproteins are analysed by matrix assisted laser desorption time of flight mass spectrometry (MALDI-TOF). This permits the determination of the number of covalently added molecules of antigen per molecule of carrier protein, together with the molecular weight distribution (maximum and minimum numbers of residues per molecule). Generally, neoglycoproteins have an average of 10 to 12 carbohydrates per molecule of protein, with a range of between 8 to 20. (The saturation point is 8-10 carbohydrates per molecule of protein, above this the feedback obtained is no greater.)
If you would like to discuss your specific requirements, please contact us and we will be happy to provide you with a quotation.