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Custom Peptide Synthesis Service FAQ


Answers to frequently asked questions (FAQs) about Custom Peptide Synthesis Service


 

FAQ Categories
• Peptide synthesis
• Peptide handling, storage and solubilization
• Documentation
• Product offering

Peptide synthesis

What type of peptide synthesis protection chemistry does Thermo Scientific use?
We routinely use solid-phase synthesis using Fmoc protection chemistry. However, for complex syntheses, we also offer synthesis in solution.
• Visit our Peptide Synthesis page in the Protein Methods Library for more information.

Is it possible to synthesise every peptide sequence?
In contrast with oligonucleotide synthesis, peptide synthesis is much more difficult, because the 20 standard amino acids display various chemical and physical properties that sometimes hinder proper coupling. An example of a difficult amino acid chain to synthesize is one with long stretches of aliphatic amino acids. If our production team identifies peptide sequences in your order that are likely to be impossible to synthesise, we will work with you to find possible alternatives.
• Amino Acid Physical Properties

What are the standard delivery times?
Delivery times strongly depend on the scale, purity, order volume and peptide sequence. In general, though, we usually ship crude peptides within 1 week of receiving your order, while delivery times for purified peptides or larger amounts can vary from 2 to 5 weeks.

 

Peptide handling, storage and solubilization

How are the peptides supplied?
Unless otherwise requested, all peptides are delivered as lyophilized trifluoracetic salts with free amino and carboxy termini. N-terminal acetylation and C-terminal amidation is free of charge but must be requested when ordering your peptide(s).

How should peptides be stored?
Upon receipt, we recommend preparing single-use aliquots (if necessary) and storing the products immediately at -20°C. In this manner, the peptides are stable for several years. Solubilized peptides should be used immediately, becaue they are unstable (the lower the concentration, the more unstable the peptides are). Any remaining peptides in solution should be re-lyophilized for longer storage.

How should peptides be handled?
Gloves should always be worn when working with peptides to avoid contamination (e.g., enzymatic, bacterial, etc.). As many peptides are light-sensitive, they should also be protected from direct light. Repeated freeze-thaw cycles also should be avoided.

How are peptides solubilized?
Peptides are complex biomolecules, and each peptide has unique chemical and physical properties because of the unique amino acid composition. Although some peptides are easy to dissolve in aqueous solutions, peptides are often insoluble, especially when they contain long stretches of hydrophobic amino acids.

General guidelines to solubilize peptides:
• Because of the unique solubility of each peptide, we recommend first testing the solubilization of each peptide with a small amount of product.
• Always use sterile water or buffer (phosphate buffered saline [PBS], Tris or phosphate, pH 7) to solubilize peptides.
• Oxygen-free solvents should be used to solubilize peptides containing cysteine, methionine or tryptophan, which are susceptible to rapid oxidation.
• Allow the peptide to warm to room temperature (preferably in a dessicator) prior to adding the solvent of choice.
• Solubilization can be improved by warming (<40°C) or sonicating the solution.
• If you need to increase the pH of the solution, use only very weak bases to prevent immediate inactivation or racemization.

Guidelines to solubilize hydrophobic peptides:
• If the product proves insoluble in aqueous buffers due to high hydrophobicity, dissolve a small amount of product in the smallest possible volume of a 50% (v/v) DMSO/water mixture. Then add the desired aqueous solution until the target concentration is achieved.
• If the product precipitates during this process and cannot be redissolved by adding dimethylsulfoxide (DMSO), then lyophilize the peptide and try again, adding a little more 50% DMSO than the previous attempt.
• If DMSO interferes with your experimental system, dimethylformamide (DMF) or acetonitrile can serve as alternate solvents.

Can I predict if a peptide is soluble in aqueous solutions?
While the amino acid sequence determines the chemical and physical properties of each peptide, we can only offer general guidelines for predicting the solubility of a peptide:
• Peptides shorter than 5 residues in length are usually soluble in aqueous buffers, except when the entire sequence consists of hydrophobic amino acids (A, W, L, I, F, M, V and Y).
• Hydrophilic peptides containing >25% charged residues (R, H, K, E and D) and <25% hydrophobic amino acids are usually soluble in aqueous buffers.
• Hydrophobic peptides containing ≥50% hydrophobic residues may be insoluble or only partly soluble in aqueous solutions. In these cases, we recommend using stronger solvents like DMSO, DMF or acetonitrile.
• Peptides containing a very high (>75%) percentage of D, E, H, K, N, Q, R, S, T or Y are capable of forming intermolecular hydrogen bonds (crosslinking), thus forming gels in aqueous solutions. These peptides should be solubilized as with hydrophobic peptides (see above).
• To minimize solubility problems, optimization of the peptide sequence may be necessary.

What peptide parameters are influenced by amino acid composition?
The ability to synthesize the peptide and its solubility, stability, and overall charge.
• Visit our Peptide Design page in the Protein Methods Library for more information.


Documentation

What kind of documentation comes with my order?
Every peptide is accompanied with its individual Quality Certificate, which contains specific information on the synthesized sequence, purity and amount of peptide together with the mass spectrometric and HPLC analysis. Crude peptides only come with the mass spectrometric analysis. Every peptide shipment additionally comes with our "Handling and storage guidelines for peptides". On request, we can also send you a Material Safety Data Sheet (MSDS).


Product Offering

What peptide scales are available?
We routinely synthesize peptides from 2 to 100mg. Other scales are avaiable upon request.

What purity grades are available?
We offer crude peptides as well as those with purities greater than 70%, 80%, 95% and 97%, and all peptides come with documentation of the indicated purity (see Documentation above).

What modifications are available?
See our comprehensive list of Peptide Modifications.

Do you offer Good Manufacturing Practice (GMP) peptides?
We do not offer GMP peptides. However, for customers that require higher documentation and reliability than what is provided with our standard products, we offer Interactiva Manufacturing Practice (IMP) peptides. Contact customer service for details (see below).

For all peptide-related customer service or technical support

North America

Email: peps@thermofisher.com
Phone: 1-888-412-2225 or 1-256-704-4848

Europe and all other regions

Email: services.biopolymers@thermofisher.com
Phone: 49-731-29870 (Germany)

 

 

 

 

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