In vitro and in vivo thermostability of BAAT N-acyltransferase activity. Purified recombinant wild-type hBAAT (filled circles), hBAAT-S (open squares), and hBAAT-SKL (filled squares) were assayed for BAAT N-acyltransferase activity after incubation at 42°C for 0, 15, 30, 45, 60, or 120 min. Data are expressed as a percentage of control activity (0 h at 42°C) for each BAAT form.