In general, ???????peptides should first be dissolved in distilled, preferably sterile water. If solubility is a problem, try
the following solution:• Sonication is helpful to dissolve the peptide.
• Small amounts of dilute (10%) aqueous acetic acid (for basic peptides) or aqueous ammonia (for acidic peptides)
may help dissolution of these peptides.
• It is also recommended that the peptide be dissolved to the highest possible concentration, and then diluted with
water or buffer to the working concentration.
• (Note: The buffer should be added only after the peptide is completely in solution form, because salts may cause
aggregation and create further solubility problems.)
Preparation for Use
When preparing the peptide for use, please observe the following steps to maintain peptide quality:
• Warm the peptide to room temperature, prior to opening and weighing out portions of the peptide. (Recommended
warm up time is minimum 40 minutes.)
• Weigh out desired quantity of peptide quickly.
• Reseal vial tightly.
• The experiment should be carefully planned to minimize opening of the peptide vial.
• Store the remaining peptide in freezer, preferably below -20°C and under dry conditions.
• Always use fresh desiccant pouches when storing packaged or bulk peptides to absorb moisture from air in bag and
freezer.
Peptide Storage
Peptides are delivered in lyophilized form and often hydroscopic. Absorption of water will decrease stability of the
peptide and may reduce overall peptide content. For best results, please note:
• Maintain a dry environment and use a desiccator.
• Upon arrival, always store lyophilized peptide in a freezer at -20°C for maximum stability.
• Avoid using a frost-free freezer, because changes in moisture and temperature may affect peptide stability.
• Short-term temperature changes that occur during shipping should not affect product life or efficacy.
Storage of Peptides in Solution
It is not recommended to keep excess peptides in solution. The shelf life of peptides in solution is very limited, especially
for sequences containing cysteine, methionine, tryptophan, asparginine, glutamine, and N-terminal glutamic
acid. In general, aliquot the necessary amounts of peptide for the day and re-lyophilize remaining portions. If storage
of peptides in solution is absolutely unavoidable, use sterile buffers at pH 5-6 and store aliquots at -20°C to prolong
the storage life of peptides in solution.
We recommend if peptide solution cannot be used all at once to re-lyophilize unused portion. Peptide is more stable
in powder form.Net Peptide vs. Gross Peptide Weight
When ordering or receiving quotations for peptides, it is important to specify the amount in either gross or net peptide
weight. In most cases, peptides are sold in gross peptide weight unless otherwise requested.
After purification and final lyophilization, the white peptide powder will contain some counter ions, residual trace
solvents, and moisture. The most common counter ions include trifluoroacetic acid (TFA), sodium (Na), phosphate
(PO3), and acetic acid (AcOH). If a TFA buffer was used during the final purification, for example, it can form a salt with
amino groups on the side chains of lysine and arginine residues or on the amino terminus of the peptide. TFA salt,
the residual traces of TFA can cause the pH of your solution to drop below 7. For this reason, it is often necessary to
check and adjust the pH of your peptide solution to reach your desired pH. In addition to counter ions, peptides can
absorb and maintain a particular amount of moisture or water content. This depends primarily on the hydroscopic
nature of molecule. As a general rule, a greater percentage of hydrophilic residues contained in your sequence, the
more hydroscopic the peptide will be. It is generally impossible to render a peptide completely anhydrous.
When calculating the concentration of peptide solution for your biological assays it is essential that you account for
peptide content. The peptide content can be determined by amino acid or nitrogen analysis for each lot of material.
It is important to note that the peptide content normally can vary from lot to lot - unless the process has been
validated. To ensure consistent peptide concentrations, please always substract the nonpeptide weight when determining
what volume of solvent to dissolve your peptide. For example, to make a 1mg/ml solution of peptide with a
content of 80%, you would use 800ul of solvent instead of 1000ul.