Variable region sequence and characterization of monoclonal antibodies to a N,N',N"-trisubstituted guanidine high potency sweetener.

A library of monoclonal antibodies (mAb) was made against a trisubstituted guanidinium sweetener (N-(p-cyanophenyl)-N'-(diphenylmethyl)guanidine acetic acid) that is 200,000 times sweeter than sucrose on a molar basis. The mAb were characterized in terms of their ligand affinities, H- and L-chain isotypes and V-region amino acid sequences. Nine of these mAb were found to have dissociation constants in the nanomolar range. The H-chain V-regions were cloned, sequenced and found to be derived from five different families (Q52, X24, J558, 7183 and 36-60). L-chain V-regions were found to be derived from three kappa families (V kappa-4/5, V kappa-19/28 and V kappa-1) and one lambda family (V lambda-1). Amino acid homologies with these family sequences ranged from 51-91% for heavy chains and 69-97% for light chains. Sequence comparisons with Ig structures solved by X-ray diffraction were made in order to identify canonical structures. Identification and localization of combining region tryptophans (L:96W and H:33W) for two mAb (NC10.8 and NC6.8) supported previous ligand-induced tryptophan fluorescence quenching observations.