Reaction of proteins with glutaraldehyde

Glutaraldehyde was found to react with the α-amino groups of amino acids, the N-terminal amino groups of some peptides and the sulfhydryl group of cysteine. The phenolic and the imidazole rings of tyrosine and histidine derivatives were partially reactive. With proteins such as bovine serum albumin, ovalbumin and human gamma globulin, glutaraldehyde reacted predominantly with the ϵ-amino groups of lysine to form mainly intermolecular cross-linkages. Some reaction, however, did occur with tyrosine, histidine, and sulfhydryl residues. The soluble aggregated proteins were capable of reacting with antibodies against their respective native proteins. Glutaraldehyde was also capable of conjugating ovalbumin to bovine serum albumin and the product was found to contain only minor contaminants of aggregated ovalbumin and bovine serum albumin.