Figure 6.

Effects of alanine substitutions on ligand-linked dimerization are modest but non-additive. A. Absorbance versus radius profiles for bio-5′-AMP bound M211A variant prepared at 40, 50, and 60 μM and centrifuged at 21,000 (□) and 24,000 (○) rpm along with the best-fit curves obtained from the global analysis of nine datasets to a monomer–dimer model using WinNonLin.³ The lower panel shows the residuals of the fits for each of the six datasets that are shown. B. Energetic penalties to holoBirA dimerization indicated as dark gray bars with anticipated additive effects of multiple alanine substitutions provided as the sum of the dark and light gray bars.