An effective method for the synthesis of neoglycoproteins and neogangliosideproteins by use of reductively aminated sulfhydryl-containing carbohydrate conjugates.

A highly effective method for the synthesis of neoglycoconjugates has been developed. The technique is based on two steps. First, a sulfhydryl group is introduced into the carbohydrate by reductive amination with cysteamine, and secondly the sulfhydryl group carrying carbohydrate is coupled to a protein or carrier via a disulfide bridge. The method was used to couple sialic acid-containing carbohydrates such as N-acetylneuraminyllactose and the carbohydrate moieties of gangliosides (GM1, GM3 and GD1b) to bovine serum albumin. Biological functionality of the generated GM1- and GD1b-neoglycoprotein was demonstrated by a choleratoxin-binding assay and an immunoassay, respectively. The applicability of neoglycoconjugates for the quantification of gangliosides in solution by a competitive assay is shown.