protein concentration

Simon Penson spensonwanson at
Wed Sep 27 10:30:26 EST 1995

In article <44ao4g$8l8 at>, James.Fethiere at BRI.NRC.CA (James
Fethiere) wrote:

> What would be the correct way of getting protein concentration from the
> extinction coefficient.  I have been told to just read the absorbance at
> 280, sum up the individual extinction coefficients of Tyr, Trp, and Cys,
> and use the formula to get my concentration.  This seems pretty reasonable
> to me, but i was wondering how the accuracy of this method compares to the
> standard protein assay. 


There is no such thing as an `accurate' protein assay. Each protein
behaves too differently in each assay system you choose. So, depending on
how much time you want to spend on it, you'll get a rough or not so rough
idea. The most accurate protein estimation method is the Kjeldahl total N
method, but nobody uses this for routine biochemistry.

Don't sweat it!


Simon Penson
Plant Biology
UC Berkeley
(510) 642 8064

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