Immunochemical characterization of polylysine conjugates containing reductively aminated cellulose oligosaccharides

Abstract

Neoglycoproteins prepared by direct reductive amination of cellobiose, cellotetraose and cellopentaose to polylysine, were found to be effective antigens in rabbits, and the antisera were found by quantitative inhibition techniques to be predominantly hapten specific. Several analogs incorporating various structural features of the carbohydrate hapten were synthesized and examined as inhibitors of the precipition reaction between the neoglycoproteins and homologous antisera in order to identify those structural features of the hapten important in antibody recognition. Antibodies to the reductively aminated cellobiose-polylysine conjugate were found to recognize the terminal β-glucopyranosyl residue, theacyclic reduced glucose residue, and the secondary ammonium linkage and methylene arm of the lysyl residue of the hapten. Antibodies to the cellotetraose-polylysine conjugate, in contrast, displayed no recognition for the secondary ammonium linkage region; they were found to recognize the non-reducing terminal β-glucopyranosyl residue, the two internal β1,4-linked glucopyranosyl residues, and the reducing end glucose residue in anacyclic orcyclic form. Inhibition studies with antisera to the cellopentaose-polylysine conjugate again established that there was no recognition of the secondary ammonium linkage region, and demonstrated that the upper limit to the size, of the antibody combining site was four β1,4-linked glucopyranosyl residues.