Thermally Induced Changes of Lipoate Acetyltransferase Inner Core Isolated from the Bacillus stearothermophilus Pyruvate Dehydrogenase Complex

Incubation at 70°C 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 thermostabilities, but they were different in the recovery of enzyme activity after incubation with 1.2-2.0 M guanidine hydrochloride and its subsequent removal; the core was hardly recovered, but X was well recovered.