I'm a beginner in ITC, does anyone have an idea why when measuring the heat of dilution and in measuring the interaction of HSA with the drug or even with the buffer itself, the curve goes up? HSA measurement at HEPES pH 7.4 and pH 6 give similar results. Different buffer concentrations and different ionic strength do not solve the problem...
I dont understand what dou you mean with "the curve goes up".
You mean de peaks of each injection of the ITC needle?
I am not sure what you exactly mean, but a slight variation in the ionic strength, salt concentration or the temperature of the cell sample and titrant, in this case the HSA with the drug, can have impact on the dilution heat.
Also if you buffer have organic solvent, it might also interfere with the heat, comparative to the reference cell.
Make sure all the samples are at same temperature, in same buffers and degassed appropriately before starting.
Providing images from the assays, and some information on the experimental conditions and the experimental setup, illustrating whatever problems you are experiencing in your assays will help a lot to figure out the source of the problem.
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