IMMUNOLOGICAL CHARACTERIZATION OF FERREDOXIN AND METHYL VIOLOGEN INTERACTING DOMAINS OF GLUTAMATE SYNTHASE USING MONOCLONAL-ANTIBODIES

Three monoclonal hybridoma cell lines were selected by the epitope spe cificity for the electron donor (ferredoxin and methyl viologen) inter acting domains of glutamate synthase (EC 1.4.7.1) from Nicotiana tabac um L. cv Xanthi. The monoclonal antibodies (McAbs) inhibited the gluta mate synthase reaction dependent on either reduced ferredoxin (Fd) or methyl viologen, or both Fd and methyl viologen as electron carrier. T he three McAbs cross-reacted with the glutamate synthase polypeptide b y western immunodetection. Competitive ELISA assays using two of these McAbs as either the first or the second McAb indicated that the three McAbs share a common epitope specificity for the reductant interactin g sites. It is concluded that the electron donor recognition sites of glutamate synthase are shared with respect to the Fd- and methyl violo gen-interacting domains.