Protein assay problems

[The Grouchybeast]

Henk Veldman wrote:

> The Bio-Rad DC Protein Assay (a variant of Lowry), when done in microtiter
> plates,  uses 5 ul of sample and will tolerate at least up to 1 % of SDS. It
> is, however, incompatable with mercaptoethanol and you need a protein
> concentration in the 0.1 to 1.5 mg/ml range.

I tried that assay, but a 1:10 dilution of sample was right down at the
end of the calibration curve.  Actually, I wasn't convinced it wasn't
just interference in the assay by SDS or Tris.  

If I used neat protein in the assay, I wouldn't have enough to do any
replicates of the sample - I like to do triplicates at a minimum.  Plus,
there would then be >1% SDS in the sample.

Thanks for the suggestion, though.

> Henk

love
Anna
-- 
I see you standing there, far out along the way,
   I want to touch you but, the night becomes the day.
I count the words that I am never going to say,
   And I see you, in midnight blue.    (ELO - Midnight Blue)