Molecular requirements for hapten binding to antibodies against glutamate and aspartate.
Molecular requirements for hapten recognition by antibodies raised in rabbits against glutaraldehyde conjugates of L-glutamate and L-aspartate were determined in enzyme immunoassays by measuring the displacement of binding of glutamate and aspartate, respectively, by a large number of selected haptens to two anti-glutamate and two anti-aspartate sera. The results indicate that N-terminal modifications of the amino acids, such as the presence of an N-acetyl or N-carbamyl group or the addition of a second amino acid to form dipeptides with C-terminal glutamate or aspartate, are tolerated to variable degrees, more so by the aspartate than the glutamate antisera. The antibodies possess point-to-point recognition sites for the two carboxyl groups present in both amino acids. Strong shape complementarity between the amino acids and their respective binding sites is suggested by the lack of recognition of the appropriate D stereoisomers by any of the antibodies. Changes in the distance between the two carboxyl groups, or modification, replacement or loss of either or both carboxyl groups, strongly reduce or eliminate binding. Based on these results, we suggest that other antibodies raised to similar conjugates of these amino acids are likely to share similar recognition characteristics. In addition, the results provide a rational background for the evaluation of antibody specificity and the interpretation of results in immunocytochemical studies using antisera to glutamate and aspartate.
Department of Cell Biology and Anatomy, University of North Carolina, Chapel Hill 27599.
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Abdullah
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Ordronneau
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Petrusz
D000595:Amino Acid Sequence; D000818:Animals; D000918:Antibody Specificity; D000937:Antigen-Antibody Reactions / Q000276:immunology*; D001224:Aspartic Acid / Q000276:immunology*; D003429:Cross Reactions; D004151:Dipeptides / Q000276:immunology; D005971:Glutamates / Q000276:immunology*; D018698:Glutamic Acid; D005976:Glutaral / Q000276:immunology; D006241:Haptens / Q000276:immunology*; D007124:Immunoenzyme Techniques; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011817:Rabbits / Q000276:immunology; D017459:Receptors, Amino Acid / Q000276:immunology
D004151:Dipeptides; D005971:Glutamates; D006241:Haptens; D017459:Receptors, Amino Acid; D001224:Aspartic Acid; D018698:Glutamic Acid; D005976:Glutaral