Antibody specificity: a 270-MHz hydrogen-1 nuclear magnetic resonance study of the binding of dinitrophenyl compounds to the VL dimer of protein 315

Abstract

The binding of dinitrophenyl (DNP) compounds to the VL dimer of protein 315 (IgA/X2) results in small perturbations of about ten resonances in the aromatic region of the 270-MHz 'H NMR spectrum of the protein. From a comparison of the chemical shifts of these resonances with the chemical shifts of resonances which are affected by the binding of DNP compounds to the Fv fragment of protein 315, it is concluded that the conformation of combining site residues in the VL domain of the Fv fragment is maintained in the VL dimer. The binding of DNP compounds to the VL dimer is therefore considered to reflect the retention of structural features important in determining the specificity of the Fv fragment and not the fortuitious creation of a binding site. These findings provide a structural explanation for the observation that antibodies with a X2 light chain are contained in the anti-DNP response of BALB/c mice [Cotner, T., &