Thermally induced changes of lipoate acetyltransferase inner core isolatedfrom the Bacillus stearothermophilus pyruvate dehydrogenase complex

Incubation at 70 degreesC converted the Bacillus stearothermophilus lipoate acetyltransferase inner core into an unidentified active molecular form, X , yielding an inactive aggregate, The core and X showed similar thermostabi lities. but they were different in the recovery; of enzyme activity after i ncubation with 1.2-2.0 M guanidine hydrochloride and its subsequent removal ; the core was hardly recovered, but X was well recovered.