| The gene formed an operon that consisted of four genes , pdhA , pdhB , pdhF , and pdhX , which are tandemly arranged in the order of pdhA F 10 B . ^^^ SDS PAGE analysis of the purified recombinant enzyme showed four different bands corresponding to alpha ( 54 kDa ) , beta ( 43 kDa ) , gamma ( 19 kDa ) , and delta ( 8 kDa ) subunits encoded by pdhA , pdhB , pdhF , and pdhX , respectively , and the molecular ratio of these subunits was determined to be equal . ^^^ |