Frequently Asked Questions

Handling and Storage of Peptides

Peptides have widely varying solubility properties. The main problem associated with the dissolution of a peptide is secondary structure formation. This formation is likely to occur with all but the shortest of peptides and is even more pronounced in peptides containing multiple hydrophobic amino acid residues. Secondary structure formation can be promoted by salts. It is recommended first to dissolve the peptide in sterile distilled or deionized water. Sonication can be applied if necessary to increase the rate of dissolution. If the peptide is still insoluble, addition of a small amount of dilute acid or acidic buffer(for basic peptides) or base or basic buffer (for acidic peptides) can facilitate dissolution of the peptide.

For long-term storage of peptides, lyophilization is highly recommended. Lyophilized peptides can be stored for years at temperatures of -20C or lower with little or no degradation. Peptides in solution are much less stable. Peptides are susceptible to degradation by bacteria so they should be dissolved in sterile, purified water.

Peptides containing methionine, cysteine, or tryptophan residues can have limited storage time in solution due to oxidation. These peptides should be dissolved in oxygen-free solvents. To prevent the damage caused by repeated freezing and thawing of peptides, dissolving the amount needed for the immediate experiment and storing the remaining peptide in solid form is recommended.

Weight of peptide on certificate of analysis refers to gravimetric weight and is not associated with the net peptide content. The peptide content can only be determined via analytical chemistry techniques. Midwest Bio-Tech offers peptide content analysis using amino acid analysis and this service is available upon request.

  • P.O. Box 6153, Fishers, IN 46038
  • Phone: 317-841-7463
  • Toll Free: 800-772-2798
Midwest Bio-Tech, Inc
Midwest Bio-Tech, Inc