TCA precipitation - What is the final concentration of TCA ? (Apr/18/2002 )

Hi,
What is the final concentration of TCA for protein precipitation that would give a good result? I have read some protocols that use 10% but some use 20%.  And what is the rational of choosing the concentration? Why no one use 40% or higher?

Thanks in advance,
Jack

Jack,
5, 10, and 20% are often used  as convention. All one needs to do is shift the pH such that the protein denatures and comes out of solution. Higher concentrations are not used to avoid acid hydrolysis of the peptide backbone.

What  is the rational of choosing the percentation? Does anybody explane about it?