[RASMB] conc. of membrane proteins

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

Dear Holger,

It may be a counsel of perfection, but we usually measure the absolute 
concentration of a solution by amino acid analysis and then calibrate every 
other method we are using for concentration determination from this 
solution.  It is certainly true that many of the standard methods give 
values which are out, for membrane proteins, when one does this.

Jo

--On Tuesday, February 17, 2004 11:54 am +0100 Holger Strauss 
<strauss at fmp-berlin.de> wrote:

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> Hello everybody,
>
> it seems that the theoretical extinction coefficients (Edelhoch, Gill &
> van Hippel, etc) are a very rough guess at best for membrane proteins, as
> they are calculated from soluble proteins in aqueous solutions of from
> reference compounds in aqueous solutions. Now, how to determine the
> concentration of a membrane protein solution nondestructively and
> precisely? Is there a reference set of exct-coefficients for membrane
> proteins around? What about dn/dc? Is the one-value-fits-all of 3.29 valid
> for membrane proteins?
>
> Best wishes to all, Holger
>
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> Holger Strauss
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P.J.G. Butler,
MRC Laboratory of Molecular Biology,
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Tel. +44 (0)1223 402296