Production and Characterization of Monoclonal Antibodies to Bovine Brain GABA Transaminase

Monoclonal antibodies (mAbs) have been produced to bovine brain γ-aminobutyric acid (GABA) transaminase (GABA-T). The antibodies recognized a single band of molecular weight of 50 kDa on an immunoblot with purified GABA-T. When unfractionated total proteins of bovine brain homogenate were separated by SDS-PAGE and immunoblotted with the mAbs to check the specificities of the antibodies, a single protein band of molecular weight 50 kDa was revealed. In order to know the cross-reactivities among mammalian and avian brain GABA- T enzymes with the antibodies, animal brains were removed, and total proteins of the brain homogenates were extracted and immunoblotted. The immunoreactive bands on Western blots appeared as a single protein band of Mr 50 kDa and were the same in all animal tested except in chicken. The result suggests that the mammalian brain GABA-T enzymes are immunologically related each other and could be similar in protein structure, but the chicken enzyme is immunologically distinct from mammalian enzymes. When the purified enzyme was incubated with the mAbs, the GABA-T enzyme activity was inhibited up to maximum of 21%.