Precise protein concentration

[Jean-Francois Huaulme]

Hi,

You may use the coloration whith Silver Nitrate (sensibility = 1 to 10 ng)
I use this method to quantifiate a membrane receptor purified, after an
electrophoresis on acrylamide gel.


On Wed, 6 Jan 1999, Lena Zaitseva wrote:

>  Hi,
>      We purified a membrane protein in the presence of non-ionic
> detergent. Now we need to calculate precise protein
> concentration. It appeared to be a real problem.
>      Bradford method doesn't work at all. BCA method looks better, but
> with BSA as control it doesn't give us reliable results
> (there is no linear dependence of OD from concentration of our protein).
> For UV-method it would be nice to unfold  protein to
> get the maximum absorbency at 280 nm. However, guanidine-HCl and SDS
> lead to the protein aggregation. We tried also
> make quantitative amino-acid analysis of the protein, but  presence of
> high salt concentration (1.5 M) and glycerol in the sample
> buffer is a problem in that case.
>      Do you have any idea about that?
>      Thanks for your suggestions.
>      Lena.
>