CBD interactions with DIV-S6, using ITC. (a) Representative ITC traces for titration of 100 mM lidocaine into 1 mM peptide or blank buffer. The heat signal, once the binding is saturated is the same as the blank if the blank was only measuring the interaction if lidocaine with the solution. The blank measures 3 interactions, interactions between solute molecules, solute and lidocaine and lidocaine and lidocaine. As more lidocaine is added with each injection the solution is changed. This makes the heat of interaction with in-blank trace different from beginning to end. This change is due to a change in amount of lidocaine in the solution. Because this change is progressive with each injection and that the injections into the peptide are the same volume, subtraction was used as a means to quantify lidocaine peptide interaction. (b) Representative ITC traces for titration of 40 mM CBD into 1 mM peptide or blank buffer. (c and d) The blank condition subtracted heat of titration in protein condition is shown for lidocaine (c) and CBD (d). A peak heat of 968.0 ± 23.4 kcal mol−1 was seen for lidocaine (n = 3) titration, and a peak heat of 1,022.2 ± 160.6 kcal mol−1 was seen for the CBD (n = 4) titration. Error bars are SE in mean.
