Skip to main content
. 2014 Feb 12;2(1):5. doi: 10.1002/prp2.25

Figure 4.

Figure 4

Determination of the sevoflurane (SF) affinity for the individual (Ca2+)2-loaded CaM lobes by isothermal titration calorimetry (ITC). Representative ITC experiments showing binding of antagonist W-7 with the (Ca2+)2-loaded CaM N-lobe (A) and C-lobe (B) in the presence of 20 mmol/L SF. The upper panels represent ITC raw data with each peak corresponding to an injection event. The lower panels show integrated values for W-7 binding to (Ca2+)2-CaM lobes in the presence (black squares) and absence (open red circles) of 20 mmol/L SF. Integrated values are fit to a two-site binding model, with the first high-affinity site used to determine the affinity of SF. The second binding-site is too weak to quantify accurately. The W-7 binding affinities of (Ca2+)4-CaM were observed to alter from Kd 5.5 to 18.0 μmol/L and from Kd 15.6 to 32.6 μmol/L for the C and N-lobes, respectively, upon changing the SF concentration from 0 to 20 mmol/L. The aqueous SF concentration (20 mmol/L) of the solutions utilized in the ITC experiments was confirmed by 1H NMR (Fig. S6). SF binding affinities are given in the text.