Protein w/ no Trp quantitation: help!!!

[ming at msvax.mssm.edu]

The best way to have an accurate protein conc. is the AA analysis. I would use
the AAA result without hesitation. Furthermore, if you think your protein is
pure enough, you can try ESI-MS, under which you will be surprised that your
protein is actually not pure at all:))  Good luck!


In article <4fnd38$dvi at lyra.csx.cam.ac.uk>, Luca Jovine
<lj1 at mrc-lmb.cam.ac.uk> writes:
>
>   Dear Netters,
>   
>   one of the proteins I am working on doesn't have any Trp, so measuring
>   its concentration at 280 nm doesn't work (the His absorbance is too low
>   to be accurately measured). I tried several other methods (Biorad,
>   205/210 absorbance, turbidity measurements etc...) and they all give
>   quite different values. Even amino acid analysis doesn't seem to be 
>   particularly consistent with any of the other methods, so I am very
>undecided
>   which method I should rely upon (I need a very accurate measurement).
>   Have any of you had a similar problem and found a better way to extimate
>   protein concentration, considering that my protein has to be in a Tris
>buffer
>   with DTT (otherwise it precipitates)?
>   Thank you very much in advance for your help and best regards, Luca.
>   
>-----------------------------------------------------------------------------
> 
>   Luca Jovine
>
>   Structural Studies Division, MRC Laboratory of Molecular Biology
>   Hills Road, Cambridge CB2 2QH, ENGLAND
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