BCKDH activity of reconstituted complexes with different ratios of wild-type and mutant E1. A constant amount of purified native E2 (0.75 μg) was used for reconstitution with a constant total amount of E1 (8 μg) but with various ratios of mutant and wild-type E1 (■) Amount of wild-type E1 varied as indicated without addition of mutant E1; (○) amount of total E1 kept constant (8 μg) by varying R288A and wild-type E1; (●) by varying H292A and wild-type E1; (□) by varying D296A and wild-type E1. [Reproduced with permission from J. W. Hawes, R. J. Schnepf, A. E. Jenkins, Y. Shimomura, K. M. Popov, and R. A. Harris. J. Biol. Chem. 270, 31071 (1995).]