[The form of alpha-ketoglutarate dehydrogenase showing no cooperative properties during substrate binding]

A form of alpha-ketoglutarate dehydrogenase was detected, which is characterized by the non-equivalency of active centers for substrate binding normally revealed by chemical modification techniques and typical for other enzyme forms. The properties of various forms of alpha-ketoglutarate dehydrogenase (both soluble and immobilized on Sepharose) were compared. It was shown that despite its dimeric structure the newly detected enzyme form binds alpha-ketoglutarate in a way similar to the monomer; in this case no substrate-induced non-equivalency of the subunits due to intersubunit interactions is observed. It was found that the independent functioning of the active centers of the enzyme is due to the loosening of intersubunit contacts.