Chiral interaction of a polyclonal anti-dinitrophenyl antibody with dinitrophenyl-amino acids determined by an enantioselective enzyme-linked immunosorbent assay

The enantioselectivity of the interaction of a polyclonal anti-DNP (dinitrophenyl) antiserum with a variety of DNP-amino acids has been determined by an indirect noncompetitive ELISA and the results obtained have been compared with those of an indirect competitive ELISA. The competitive ELISA offers an advantage to determine the I50 values representing the relative affinities of the investigated DNP-amino acid enantiomers. In all cases, the I50 values obtained were different for the individual DNP-amino acid enantiomers. While the l-enantiomers of ϵ-DNP-lysine, δ-DNP-ornithine, DNP-alanine and DNP-proline show a higher relative affinity for the antibody combining site than the d-enantiomers, an inverse chiral recognition was found for DNP-phenylalanine. On account of the high sensitivity of the ELISA system, the determination of small differences in the enantiomer recognition by the anti-DNP antibody is possible.