FIG. 4.

The three BZLF1 peptides self-associate as dimers. (A) The thermal stability of each peptide was measured by CD spectroscopy at the four concentrations indicated. pepB95-8 is shown as closed circles, pepA205S as open circles, and pepA206S as open diamonds. (B) The weight-average molecular weight of the three BZLF1 peptides was determined by sedimentation equilibrium centrifugation in a Beckman XL-I analytical ultracentrifuge fitted with a titanium An60-Ti rotor, using software supplied by Beckman Coulter UK. Three concentrations of each peptide were used (100 to 500 μM) in a buffer system containing 25 mM potassium phosphate, 100 mM sodium chloride, and 1 mM dithiothreitol. To relate this molecular weight to the extent of oligomerization, the calculated average molecular weight was divided by the monomer molecular weight for each peptide. The error bars show 95% confidence intervals.