[RASMB] partial specific volume of protein in guanidine and urea

[pjgb at mrc-lmb.cam.ac.uk]

Dear Yi-Ming,

I have a nasty feeling that the correct answer is to measure the density 
increment (and hence derive v-bar as well as knowing rho-0) at each 
guanidine or urea concentration.
Some years ago we were looking at the folding/dimerisation of the 
DNA-binding domain from HPV-15 E2 protein and we did measure these for a 
range of urea concentrations (Mok, Y.-K., de Prat Gay, G., Butler, P. J. & 
Bycroft, M. (1996). Equilibrium dissociation and unfolding of the dimeric 
human papillomavirus strain-16 E2 DNA-binding domain. Prot. Sci. 5, 
310-319).  They changed in a pretty linear fashion, so one could 
interpolate additional values, but I would not have been very confident 
without having measured a number of points.

Yours,

Jo

--On Wednesday, March 24, 2004 3:38 pm -0500 Yi-Ming_Li at hgsi.com wrote:

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> Hi! I want to use guanidine (4-6 mol/L) or urea (6-8 mol/L) solution for
> sedimentation velocity runs. To analyze the data with Sedfit, I need to
> have the v-bar of the sample protein in these solutions. I have obtained
> the v-bar of the protein in formulation buffer by use of density meter. As
> indicated by some authors, v-bar of protein will change in guanidine and
> urea solutions. I hope someone can tell me how to get v-bar of the protein
> in these solutions. Thanks!
> Yiming
>
>
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P.J.G. Butler,
MRC Laboratory of Molecular Biology,
Hills Road, Cambridge, CB2 2QH, UK.
Tel. +44 (0)1223 402296