Molecular probes for sweeteners: immunorecognition of superpotent guanidinium compounds

Monoclonal antibodies (MAb) were made to two different superpotent guanidino sweet tasting ligands, N-(p-cyanophenyl)-N'-(diphenylmethyl)-guanidineacetic acid and N-(p-cyanophenyl)-N'-(cyclooctyl)-guanidineacetic acid. In the present study we examined the binding specificity of three MAb clones (denoted as NC10.7, NC10.13, and NC37.3). The isotypes of these MAb were determined to be IgG1 kappa for NC10.7 and NC37.3, while NC10.13 was IgG2b, kappa. The dissociation constants for the MAb were 19 nM (NC10.7), 28 nM (NC10.13), and 16 nM (NC37.3). The binding specificity of each MAb was characterized by a competitive inhibition radioimmunoassay using related sweetener analogues. Antibodies to this family of sweet tasting compounds may be useful probes for the study of sweet taste chemistry and identification of novel sweet taste ligands.