A280 vs. protein assay?

[Jeff R. Livingstone]

In Article <Cw93uA.7H0 at freenet.carleton.ca>, at332 at FreeNet.Carleton.CA (Matt
Parker) wrote:
>
>        The BioRad assay involves the binding of a dye to protein. 
>Solutions of identical concentrations of different proteins can vary
>widely in their response. I think it's likely that your monomer and
>dimer just have different amounts of binding surface for the dye.
>
>        There are several other ways to assay proteins. Look in the
>Pierce catalog....they sell several kits, including a supposedly
>"improved" version of the BioRad (Coomassie) system, which is claimed
>to show less variability.
>
>        Good luck! I'd be interested in hearing how it turns out.

I concur with Matt's suggestion.  We've seen widely varying differences in
binding of the Bradford dye to single site mutants of the same protein!  In
our hands this assay is only good to +- 20% at best.

- Jeff
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Jeff R. Livingstone, Ph.D.                 Net:    livingst @ ncifcrf.gov
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