My peptide sequence is FFFFFFFFEEEE (F8E4). I read some guidelines for peptide handling and I firgue out DMSO is most suitable solvent for hydrophobic peptide. I try to dissolve 10 mg peptide in 500 uL DMSO but there are visible particle in solution. I would highly appreciate anyone can give me some advice to dissolve this peptide with fewest volume DMSO or any water miscible solvent.
Hi Viet, try using a sonicating waterbath to dissolve the peptide particles. If there are still particles, add another 0.5 ml DMSO.
Alternatively, you can try DMF or acetonitrile as a solvent.
Steingrimur, Thank you for your advice. I tried to sonicate and add more DMSO, but the sittuation is not improved. If I wanna dissolve in other solvent, I should remove DMSO form my peptide which is another difficult problem. Is it possible to dilute DMSO with water then lyophilize? How much is percentage of DMSO in water available for lyophilization?
Hi Viet, I'm not sure that you can lyophilize DMSO. Please ask organic chemists.
If you cant, you could add water to have the peptide precipitate and start over with other solvents.
@Hà Nguyễn: There were impurities in my peptide sample. Thus, I could not solubilize my peptide in DMSO completely. Using the new synthesized one with higher impurity, I can easily dissolve that peptide in DMSO. For removing DMSO, I dilute DMSO-contaminated sample with a large volume of water (0.5 ml DMSO + 20 ml deionized water) and lyophilize. Your lyophilizer machine should have an organic solvent-trap to avoid causing harm to the solvent-sensitive parts of machine. Regards.
From Sigma website:
DISSOLVING APPROACH FOR HYDROPHOBIC/UNCHARGED PEPTIDES
The above recommendations based on the charged nature of the peptide will likely be inadequate for dissolving peptides containing more than 50% hydrophobic residues in their sequence, neutral peptides with less than 25% charges, and/or peptides that has less than 10% charges. Under these conditions, the use of organic solvents is recommended, such as acetonitrile (ACN), dimethylsulfoxide (DMSO), or dimethylformamide (DMF).
Note: peptide sequences containing Cys (C) and Met (M) are unstable in DMSO.
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