Skip to main content
. Author manuscript; available in PMC: 2016 Apr 1.
Published in final edited form as: Methods. 2014 Dec 2;76:137–148. doi: 10.1016/j.ymeth.2014.11.012

Figure 2.

Figure 2

Titration experiments of α-chymotrypsin (CT) in 200 µl cell of an ITC200 MicroCal calorimeter (GE Healthcare) being titrated with 1.8 µl aliquots of soybean trypsin inhibitor (SBTI) [29]. With 20 µM CT in the cell and 83.7 µM SBTI in the syringe (red), a well-formed transition is observed. By contrast, with 22.7 µM CT in the cell (allowing locally for a concentration error) and 68.4 µM SBTI in the syringe no saturation is achieved, whereas with 3 µM CT in the cell and 83.7 µM SBTI in the syringe saturation is achieved too quickly. It is advantageous to include all experiments into a gITC analysis (solid lines), rather than solely analyzing the single well-formed data set, as reflected in the narrower confidence intervals of the binding parameters. For example, the confidence interval for ΔHAB of the first site is 2.9 – 19.6 kcal/mol based on the red trace alone, and 3.4 – 6.3 kcal/mol for the joint analysis of all traces (see text).