Handling Synthetic Peptides

1. How should I store and handle my synthesized peptides?

Peptide storage guidelines: Peptides should be stored in lyophilized form at -20°C or preferably at -80°C in a sealed container with desiccant in order to minimize peptide degradation. Under these conditions, the peptide can be stored for up to several years and the following activities can be prevented such as bacterial degradation, secondary structure formation, and oxidation.

Open the package: It is better to equilibrate the peptides to room temperature in a desiccator prior to opening and weighing. Failure to warm up beforehand can cause condensation to form on the product when the bottle is opened and this will reduce the stability of the peptide products.

Weigh peptides: Weigh out you needed quantity of peptide quickly and store all unused peptide at -20°C or less. Sequences containing cysteine, methionine, tryptophan, asparagine, glutamine, and N-terminal glutamic acid will have a shorter shelf life than other peptides.

2. How should I dissolve peptides?

It is necessary for you to test a portion of the synthesized peptide first before dissolving the entire peptide sample. You may need to test different solvents until you find an appropriate one. It is necessary to sonicate the peptide solution because sonication enhances solubilization.

1. If the peptide is acidic, add 0.1M ammonium bicarbonate to dissolve the peptide and add water to the desired concentration.
2. If the peptide is basic, add 25% acetic acid to dissolve the peptide and add water to the desired concentration.
3. If peptides are still insoluble, add acetonitrile to 20 %(v/v), and sonicate the sample.
4. If, after sonication, the peptide has not dissolved completely, lyophilize and remove the volatile buffer solution such as water, acetic acid or acetonitrile. When the sample is completely dry, dropwisely add DMF or DMSO until the peptide dissolves. Slowly dilute the solution with water to approximately 10% (v/v) DMF or DMSO. Dilute the stock solutions to the same peptide concentration.
5. In order to prevent or minimize peptide degradation, store the peptide in lyophilized form at -20°C or preferably at -80°C. If the peptide is in solution, freeze thaw cycles should be avoided by freezing individual aliquots.