Figure 1.

(A) Various glycan classes exist such as glycosaminoglycans (GAGs), glycosphingolipids (GSLs), glycoRNA, free oligosaccharides, and glycoproteins. (B) A distinction can be made in various characterization categories of the latter glycan type. Namely, glycoproteins can be analyzed intact using a top-down method or a middle-up approach that can be used to study the subunits of (monoclonal) antibodies. Other methods include enzymatic digestions, which either cleave the protein into (glyco)peptides, also known as the bottom-up approach, or cleave the glycan portion from its conjugate (released glycan analysis). The latter two are currently the only characterization approaches that can be processed and analyzed in a HT manner. Several enzymes are available for GAGs which will result in disaccharides (indicated by the scissors), while enzymes available for GSL analysis will release the glycan headgroup from the lipid portion (indicated by the scissors).