How to precipitate short peptides?

Emir Khatipov khatipovNO at
Mon Oct 8 19:32:47 EST 2001

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).

Thanks for ideas.
Emir Khatipov
University of Chicago

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