MOLECULAR RECOGNITION OF A MONOCLONAL-ANTIBODY (AC1106) CROSS-REACTIVE FOR DERIVATIVES OF RU(BPY)(3)(2+) AND RU(PHEN)(3)2+

The characterization of a monoclonal antibody (AC1106) elicited via im munization with a Co(dmbpy)-(bpy)(2)(3+)-methyl viologen hapten (1) is described. AC1106 was found cross-reactive for a variety of luminesce nt ruthenium(II) metal complexes which served as useful probes to inve stigate the molecular recognition properties of this antibody. AC1106 was found to be specific for methylated derivatives of Ru(bpy)(3)(2+) and Ru(phen)(3)(2+) in the order of Ru(dmbpy)(3)(2+) > Ru(dmbpy)(bpy)( 2)(2+) > Ru(dmphen)(3)(2+) > Ru(bpy)(3)(2+) much greater than Ru(phen) (3)(2+). The affinities of AC1106 for these metal complexes were found to range from greater than or equal to 5 x 10(7) to less than or equa l to 1 x 10(3) M(-1). When bound (>98%) by AC1106, the luminescence de cay traces for the racemic Ru(dmbpy)(3)(2+) and Ru(dmbpy)(bpy)(2)(2+) gave a satisfactory fit to a single-exponential decay process. Further more, D2O/H2O experiments with Ru(dmbpy)(3)(2+) indicate that AC1106 p rotects approximately 70% of the antibody-bound Ru(dmbpy)(3)(2+) from excited state deactivation by the solvent. Competition ELISA data indi cate that both the metal center and the methyl viologen moiety present in a Ru(bpy)(3)(2+)-methyl viologen conjugate ([Ru(mv(2+)-bpy)(bpy)(2 )](4+)) are important recognition elements for AC1106. Despite the app arent affinity of AC1106 for methyl viologen, no evidence for simultan eous binding of methyl viologen and Ru(dmbpy)(bpy)(2)(2+) inside the b inding pocket of AC1106 could be found. Rather, the addition of methyl viologen was found to result in the displacement of AC1106-bound Ru(d mbpy)(bpy)(2)(2+) from the antibody binding site.