Am 03.05.2007, 14:58 Uhr, schrieb Sai Praveen <saiprawinp from yahoo.com>:
> I have been looking at how IR spcetroscopy can be used to study
> secondary structure content of protein. Especially, when analysing the
> amide I spectrum, how do we baseline correct the interferences of
> solvent? typically water? Will DMSO help in this issue?
You would have to use pure (waterfree) DMSO since even traces of water
would show up in the spectrum, and that would surely change the protein
structure you wish to study.
One way of doing it is to use Attenuated Total Reflection. The IR-beam is
send into a medium of higher optical density then the buffer under an
angle that results in total reflection. However, under these circumstances
the light penetrates a few nm (that is, just about the diameter of a
protein molecule) into the medium (evanescent field). The protein is
immobilised at the buffer/medium interface. Since the protein
concentration there is much higher than that of water interference by
water is reduced, even though the protein is fully hydrated. Part of the
story is also that modern IR-spectrometers use Fourier-Transform
spectroscopy, resuling in much sharper peaks than the conventional types.
