?Protein Quantitation?

Kaj Stenberg kstenber at cc.helsinki.fi
Wed Sep 16 09:06:57 EST 1998


Frances <f-weis-garcia at ski.mskcc.org> wrote:
> Please help -

> We are currently quantitating our antibody concentration by two methods
> - (1) Comassie Blue G250/densitometery/Computer analysis (BioRAD's
> Molecular Analyst Program) - and - (2) the a Bradford based assay
> (BioRAD Protein Assay) - and the two methods do not always give the same

> Therefore - does anyone know of another way to quantitate the
> concentration on a purified protien that is independent of the protien
> composition - or am I wrong and should trust the bradford system more -

> Thanks for any advise or comments you can offer -

> Frances

> *************************************

> Frances Weis-Garcia, Ph.D.


I have used the absorbtion at 205 nm as an accurate (reproducible)
method. Absorbtion at 205 comes from the peptide bond and should be
independent of the aa-composition. The blank is of critical importance,
since many buffers absorb at 205nm. As I standard curve I have used
albumin dilutions.


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Kaj Stenberg, Ph. D 
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