Acetic acid in water is commonly used to dissolve peptides, especially basic ones, as it helps break up aggregates and improve solubility when distilled water alone isn't enough, often starting with dilute solutions (0.1-10%) and increasing strength if needed, with concentrations like 10-30% acetic acid effective for challenging peptides before resorting to stronger agents like TFA or urea, but always aim for the lowest effective concentration for downstream applications like HPLC or assays.
Acetic acid in water is commonly used to dissolve peptides, especially basic ones, as it helps break up aggregates and improve solubility when distilled water alone isn't enough, often starting with dilute solutions (0.1-10%) and increasing strength if needed, with concentrations like 10-30% acetic acid effective for challenging peptides before resorting to stronger agents like TFA or urea, but always aim for the lowest effective concentration for downstream applications like HPLC or assays.
How to use acetic acid with peptides
Start with water: Try dissolving the peptide in sterile distilled or bacteriostatic water first.
Add dilute acetic acid: If water fails, add a small amount of dilute acetic acid (e.g., 0.1%, 1%, or 10%) to help basic peptides (rich in Lys, Arg, His) dissolve.
Increase concentration: For stubborn peptides, gradually increase the acetic acid concentration (e.g., 10-30%) or use stronger solvents like TFA (trifluoroacetic acid).
For acidic peptides: Consider ammonium bicarbonate or ammonium hydroxide as alternatives to acetic acid.
For hydrophobic peptides: Use DMSO, acetonitrile, or methanol.
For aggregating peptides: Use strong denaturants like 6M guanidine hydrochloride or 8M urea.
Sonication: Gently sonicate or swirl/roll the solution (don't shake) to aid dissolution.
Common concentrations
0.1% Acetic Acid: A good starting point for basic peptides.
10-30% Acetic Acid: Effective for more challenging basic peptides; 10% is common in HPLC buffers.
Important considerations
Peptide sequence: Solubility depends heavily on the amino acid sequence.
Final concentration: Prepare a concentrated stock and dilute with your experimental buffer (e.g., PBS) for use.
Avoid high concentrations: Very high concentrations (e.g., 90%) can be effective but raise concerns about potential peptide degradation, so use the lowest effective concentration.
