1. How are the peptides supplied?
The peptides are delivered lyophilized. Ambient temperature should not be a problem for the lyophilized peptides. However, for maximum stability the peptides should be stored at -20°C.

2. How do I store my peptides?
The lyophilized peptides should be kept in a cool, dark place. Long term storage of the peptides should be done in a freezer at -20 to -80°C. Most peptides stored in this way will remain stable for several years.

Peptides in solution are not as stable as in the lyophilized form. Peptide solutions should be neutral to slightly acidic (pH 5-7) and stored frozen at -20°C. To avoid repeated freeze-thaw cycles it is recommended to divide the stock solution into aliquots.
o maintain sterile conditions
o Cys, Met and Trp residues tend to oxidize (oxidation-rate increases with pH)

3. How do I solubilize my peptide(s)?
The solubility of peptides is strongly dependent upon the peptide sequence. For some very hydrophobic sequences it may not be possible to use aqueous solutions without any additional organic solvents.

I. Try to dissolve the peptides in sterile water with sonication (1-10 mg peptide/ml).

II. If this fails, add acetic acid up to a total concentration of 10% (v/v) for basic peptides or aqueous ammonia for acidic peptides and sonicate. (Count the number of basic (R, H, K and free N-terminus) and acidic residues (D, E and free C-terminus) of the peptide)

III. For peptides that remained insoluble add organic solvents such as acetonitrile, DMSO or DMF up to a concentration of 20% (v/v).

NOTE: The use of organics such as acetonitrile, DMF, DMSO etc. may interfere with some biological assays. If DMSO is used, peptides with Cys, Met and Trp oxidize faster!

4. My peptide has a purity of 95% - what are the other 5%?
The peptide purity gives the percentage of the correct sequence in a given sample. The rest of the sample consists of truncated or deletion sequences.

5. What is the net peptide content of my peptide(s)?
The weight of the lyophilized peptide composes of the peptide and water weight. The water and counter-ion content vary widely, depending on the given peptide sequence. Typically 90% are peptide and the other 10% are water and counter-ions. For some highly charged peptides the water and counter-ion content can increase up to 30%.

6. What is the length of the peptides you can synthesize?
The minimum length of peptides should not be less than 5 amino acids. For shorter peptide sequences cleavage from the synthesis resin and following purification can cause problems.
The standard maximum lengths are peptides with up to 40 residues. However, upon request we will synthesize longer peptides (>60 amino acids).