Antibodies to bovine liver branched-chain 2-oxo acid dehydrogenase cross-react with this enzyme complex from other tissues and species.

Antibodies were produced in rabbits against bovine liver branched-chain 2-oxo acid dehydrogenase (BCOAD) for three reasons. First, since activity of BCOAD varies among tissues within a species, it is necessary to ascertain whether isoenzymes exist within the different tissues. Second, it is of great interest to determine the structural similarity of BCOAD among mammalian species. Third, heritable defects of this multienzyme complex are known in humans, and techniques for studying BCOAD subunit composition in cells expressing the defect include the use of specific antibodies. Antibodies produced against BCOAD inhibit complex activity and cross-react with BCOAD from various tissues and species. By using rocket immunoelectrophoresis, the complex can be quantified in mitochondrial extracts. Each subunit is immunogenic, making the detection of subunit variants possible by the combined techniques of sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and Western blotting. Finally, antibodies produced against pig heart lipoamide dehydrogenase cross-react with BCOAD, pyruvate dehydrogenase and 2-oxoglutarate dehydrogenase complexes, giving further evidence for the commonality of this subunit among these three mitochondrial complexes.