Protein w/ no Trp quantitation: help!!!

Dima Klenchin klenchin at
Fri Feb 16 17:36:00 EST 1996

In article <4g326a$pf4 at>, ming at wrote:
-->The best way to have an accurate protein conc. is the AA analysis. I would 
-->the AAA result without hesitation. 

Provided that it was executed properly :-). 
Also, it is the best way but not for routine use. The best is to measure the 
same sample by AAA _and_ by whatever method you like (Bradford in my case)
relative to BSA. After that you have a correction coefficient and can 
measure it's conc. quickly and reliably using the latter method.  
-->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!

How come? You've got to hugely overload your gel to claim you protein is pure. 
If you do and don't see any other proteins, it is pure and MS's is of no use. 
(Unless you are looking for posttransl. modifications. That's not purity issue,

- Dima

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