Figure 4. The bulge and hairpin loops of SLII contribute to high affinity UP1 recognition. Calorimetric titrations of (His)6-UP1 into various SLII structural mutants: (A) A SLIIΔLSΔBL; (B) SLIIΔBL; (C) SLIIGNRA and (D) SLIICCC. Titrations were performed at 298K. Secondary structures for each structural mutant are drawn. Processed isotherms shown along with non-linear least squares fits to a single site binding model. Average values and standard deviations of the dissociation constants (two replicates) are provided.