Fig. 2.

Isothermal titration calorimetry measurements of binding of (a) His-tagged wild-type BirA and (b) R118G variant to biotin. Measurements were performed in Standard Buffer at 20.0±0.1°C. In both measurements, the cell contained 1.7 mL of protein solution at a concentration of 1 μM. (a) 5–10 μL injections of a 250-μM biotin solution and (b) 5–50 μL injections of a 720-μM biotin solution.