ITC data for sequential dilution of 10 μl aliquots of CTD (ca. 250 μM) into buffer at 30°;C. Upper panel: raw data comparing endothermic dilution heat effects in the presence and absence of peptide (NYAD-203). Lower panel: integrated heats and theoretical fits for dilution of CTD alone (black square) or in the presence of 50 (white square), 200 (black circle), or 350 (white circle) μM peptide inhibitor. The lines are theoretical fits to a dimer dissociation model using parameters listed in Table 1. Insert: Concentration dependence of the apparent peptide affinity constant, KI,App. Linear extrapolation to zero concentration gives an estimate of KI = 45 (±5) μM for binding of peptide to CTD in the absence of peptide self-association.