How to precipitate short peptides?

Nick Theodorakis nicholas_theodorakis at
Mon Oct 8 21:09:31 EST 2001

In <wzrw7.242$P4.15821 at>, Emir Khatipov wrote:
>Does anybody remember a good method of precipitation of peptides, preferably
>using organic solvents (for easy liophylization later)? I have a bunch of
>hydrophobic peptides (weakly soluble in H2O - up to ~ 0.5-1 mg/ml, almost
>freely soluble in DMSO, acetone, etc.) I would like to re-crystallize to
>remove impurities (salts, by-products of synthesis, etc.), without losing
>too much of material, and avoiding any harsh treatments like TCA
>precipitation that may modify residues. Solubilization in e.g., acetone with
>subsequent precipitation with water is not a solution, because of partial
>solubility in water. HPLC is not quick enough, because I need a lot of
>peptide and as quick as possible, and HPLC (semi-preparative column) can
>yield ~ <10mg/run of peptide (need to recrystallize 5 x 500 mg peptides).

What about using a disposable RP column? ISTR that Waters makes a dispo C18
column called Sep-Pak that fits over a syringe. You could bind the peptide,
elute with, e.g., 100% acetonitrile, and lyophilize it down.


Nick Theodorakis
nicholas_theodorakis at


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