circular dichroism of immunoglobulin like protein

Matt Parker at332 at FreeNet.Carleton.CA
Tue Sep 5 16:42:15 EST 1995

Salvatore Sechi (SSechi at writes:
> Hello, everybody,
> I am trying to do the thermal unfolding of a protein that has two 
> immunoglobulin like domain. I follow the denaturation using the CD.
> I do 5 degrees steps and  I equilibrate the sample for 10 min. I scan from 
> 200nm  to 220nm from 22 degrees  to 85. I would like to follow the 
> denaturation at 217nm (maximum for the beta-sheet negative peak).  Supposly 
> the protein denature and the negative ellepticity at 217nm should decrease ( 
> less negative). Strangely the negative peak keeps encreasing. How would you 
> interprete this data? Does anybody know of any other protein that behaves 
> similarly? Should I go higher with the temperature? 
> Hope some body can help.
> Thanks
> Salvatore Sechi, Ph. D.
> Laboratory of Molecular Allergy and Immunology
> E-mail: ssechi at

	Is it possible that the protein might be changing from a predominantly
beta-sheet to an alpha -helical conformation? I would try extending the
range of your scans, and seeing if you get peaks at about 208 and 222 nm.

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