F A plot of the melting temperature of the indicated FICD proteins in absence (Apo) or presence of nucleotides. Shown are the mean Tm values ± SD of three independent DSF experiments. Monomeric FICDL258D (mFICD) and FICDL258D-E234G (mFICDE/G) as well as dimeric wild-type FICD (dFICD) and FICDE234G (dFICDE/G) were tested. ADP and ATP concentrations in mM are given in parentheses. 