Methods Of Peptide Dissolution

Peptide Dissolution Guide

Peptide Dissolution Process

When dissolving peptides, it is recommended to use a small amount of peptide to test the optimal dissolution method. Only when the peptide is completely dissolved can the solution be added and diluted to the final concentration. That is, dissolve first and then add the buffer. It should be noted that the peptide is added to the appropriate solvent and stirred, and no other method can be used. For general dissolution, we have the following suggestions:

• Generally, pure water or PBS is used for dissolution.
• The recommended dissolution concentration is 1mg/ml, which can be adjusted appropriately according to the properties of the peptide and experimental needs.
• If the solubility in pure water is not good, organic solvents such as acetonitrile, methanol, dimethyl sulfoxide (DMSO) can be added to help dissolve.
• Ultrasonic treatment helps break up particles and increase peptide solubility. (Note: Ultrasonic treatment will cause solution heating and peptide degradation.)
• 10% acetic acid helps dissolve basic peptides.
• 10% ammonium bicarbonate helps dissolve acidic peptides.

• Assign each acidic amino acid a value of -1 and each basic amino acid a value of +1. Then calculate the charge of the entire peptide.
• If the charge of the entire peptide is positive, it means that the peptide is basic. You can try to dissolve it with distilled water first. If it is insoluble in water, then try to dissolve it with a small amount of 10%-30% acetic acid. If it still fails, add some DMSO to solubilize it, and then dilute it with water to the ideal concentration.
• If the charge of the entire peptide is negative, it means that the peptide is acidic. Acidic peptides can be dissolved in PBS (PH 7.4). If they are insoluble, add a small amount of alkaline solvent, such as 0.1 M NH₄HCO₃, and then dilute with water to the ideal concentration. Peptides containing free cysteine should be dissolved in degassed acidic buffer because when pH>7, sulfhydryl groups will be rapidly oxidized to disulfides.
• If the charge of the entire peptide is zero, it means that the peptide is neutral. Neutral peptides are usually soluble in organic solvents. First, try adding a small amount of MeOH, CH₃CN, or (CH₃)₂CHOH. For highly hydrophobic peptides, use a small amount of DMSO to dissolve, and then dilute with water to the ideal concentration. For peptides containing free cysteine, use DMF instead of DMSO. For peptides with a tendency to aggregate, add 6 M guanidine hydrochloride or 8 M urea, and then make necessary dilutions.