Affinity Labeling of Rabbit Antisaccharide Antibodies

Rabbit antihapten antibodies against pazophenyl βlactoside and pazophenyl βgalactoside determinants have been studied with diazoniumphenyl glycosides as affinity labeling reagents. Specific labeling of the combining regions of both antisaccharide antibodies has been demonstrated by the fact that a reversibly binding hapten affords clearcut protection against the particular labeling reaction. As in earlier studies with several antibenzenoid hapten antibodies, both H and L chains are labeled. Azo spectra of H chains from both labeled antisaccharide antibodies show selective labeling at tyrosine residues; the L chains are characterized by a discrete visible spectrum which is markedly different from that of azotyrosine, azohistidine, or azolysine, the modified residues usually identifiable in azoproteins. While the affinity labeling patterns for both antisaccharide antibodies are identical, they are clearly distinguishable from those obtained in the antibenzenoid hapten systems which reveal specifically labeled tyrosine residues on both H and L chains.