The solubility of a given peptide varies depending on its amino acid sequence and modifications. AmbioPharm purifies peptides by RP-HPLC using a water and acetonitrile gradient. Here are some general tips for dissolving peptides:
- Sonication increases solubility.
- 10% acetic acid in the solvent will help dissolve basic peptides (Isoelectric Point, PI >7).
- 10% ammonium bicarbonate will help dissolve acidic peptides. (PI <7)
For very hydrophobic peptides which are sparingly soluble in aqueous solutions, water-miscible organic solvents (such as dimethyl sulfoxide (DMSO), isopropanol, methanol, and acetonitrile) should be used first. Once the peptides are completely dissolved, water may be gradually added until the desired concentration is obtained. Here is a resource for calculating the isoelectric point.
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