Abstract
The in vitro assembly of L-threonine deaminase from its constituent parts results in the formation of an inactive species of this enzyme which specifically and reversibly binds leucyl-tRNA. The native, catalytically active enzyme, which is derived from this species in the presence of maturation-inducing ligands, does not bind tRNA. The possible involvement of this protein-tRNA complex in the repression of the ilv (ADE) operon is discussed.