Control of antibody–antigen interaction using anion-induced conformational change in antigen peptide

Abstract

The binding of a monoclonal antibody to an epitope peptide was controlled by the conformational change of the epitope peptide induced by anions. We synthesized peptides in which the epitope sequence DTYRYI for the monoclonal antibody AU1 is located between amphiphilic peptides (KKLL)n and (LLKK)n. In the absence of an appropriate anion, the peptide was in a random coil state and the epitope was linear. In contrast, in the presence of an appropriate anion, the peptide exhibited an anti-parallel alpha-helical structure and the epitope was subsequently 'bent'. In the presence of 41 microM triphosphate, the association constant between the antibody and the peptide was decreased by one order of magnitude in the case of n = 3 and at least three orders of magnitude in the case of n = 4 or 5. Oligo-DNAs, as anions, dissociated the antibody-peptide complex, whereas triphosphate did not. The DNA concentrations required for 50% dissociation of the antibody-peptide complex at pH 7.5 were 4x10(-8), 1x10(-7) and 6x10(-6) M for decamer, octamer and hexamer DNA, respectively.

A piezoelectric immunosensor for Leishmania chagasi antibodies in canine serum

“…One of the most important aspects is related to the preservation of the immunoreactivity of the immobilized antigen on the surface of the quartz crystals electrode. The reuse is possible by dissociation of antigen-antibody complex using acidic or basic solution, however high concentrations of these solutions can lead to an inactivation of the immobilized molecule [31]. In this work, different dissociation agents were tested to remove the bound antibodies: 25 mM glycine-HCl (pH 2.3), 0.5 M NaCl (pH 7.0), 0.1% SDS (pH 6.5), 2 M urea (pH 7.2), and 0.2 M NaOH (pH 8.0).…”

Electrical control over antibody–antigen binding

“…Non-electrical control over antibody-antigen interaction has been exercised through an anion induced conformational change in the antigen peptide [13] and the kinetics of the interaction has been controllably accelerated by application of high hydrostatic pressures [14].…”