Proteins can be precipitated by TCA, can tripeptides, pentapeptides, hekzapeptides and other oligopeptites can be precipitated by TCA ? What is the amino acid limit ?
It seems that the physical properties, especially the hydrophobicity, of peptides is at least as important as their length with respect to their precipitation by TCA. Please see this article:
Also, the recovery of peptides by TCA precipitation may be improved by adding sodium deoxycholate or Sarkosyl as a carrier, as is the case with proteins.
http://lclane.net/text/tca3.html
Article Solubility of peptides in trichloroacetic acid (TCA) solutions