Custom Peptides

Pepscreen Peptides Peptide Impurities Recommended Peptide Purity

Sigma-Genosys offers custom peptide synthesis with a wide variety of purity levels, scales and modifications to best fit your research needs.

• Purity: IG(>50%), >70%, >80% and >95%
• Yield: 2mg-1g
• Sequence Length: Up to 40 amino acids for longer peptides please contact Customer Services Modifications: Biotin, Fluorescein, N-acetylation, C-amidation, phosphorylation, D-amino acids, MAPs, KLH/BSA conjugation, and much more

Sequence Analysis and Quotation
Supply us with your sequence of interest and we will generate a formal price quotation. An analysis will be performed on your sequence of interest and the results will be included on the quotation. If we determine that unusual procedures will be required to synthesize or purify your peptide, we will notify you immediately.

Quality Control
Every peptide is supplied with a Quality Assurance Certificate including mass spectral and HPLC analyses to verify composition and purity. All peptides are shipped lyophilized and as gross weight.

Delivery
Actual processing time is dependent on the peptide sequence, length and modifications. Please consult Sigma-Genosys for a production estimate of your peptide. Estimated delivery times are stated on all quotations.

Quality Guarantee
Sigma-Genosys guarantees the synthesis of your peptide to meet listed specifications. If you are not completely satisfied, Sigma-Genosys will either credit, reprocess, or re- synthesize your peptide(s) at no additional charge. Notification of a problem must be made within 30 days of receipt of the peptide.

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Pepscreen Peptides

PEPscreen™: Custom Peptide Libraries

Sigma-Genosys has developed a new proprietary synthesis platform using state of the art technology. This technology provides a solution to enhance your peptide screening applications. As a result, large numbers of peptides are delivered quickly and affordably, offering great value for your money. MALDI-TOF mass spec is run on 100% of your samples. Pass/Fail criteria of product is based on the specification that the desired product by mass spec must be presented as a major ion. If the desired product is not a major ion, the peptide will be remade one additional time. Mass spec images are saved as pdf files and burned onto a disc. You will receive a disc containing mass spec images for all successful peptides produced.

• Cost: $50.00 per peptide
• Yield: ~0.5-2mg
• Average Purity: ~70% (based on 15mer sequences)
• Length: 6-20 amino acid sequences
• MALDI-TOF Mass Spectrometry on 100% of peptides
• Peptides supplied lyophilized and in 96-well format (2-D bar coded tubes)
• Delivery: ~7 working days (including time for remaking "failed" peptides)
• Minimum order size is 48 peptides

NOW OFFERING MODIFICATIONS

• N-terminal biotinylation
• N-terminal acetylation
• Non-standard residue incorporation
• Disulfide bridge formation (cyclization)
• C-terminal amidation

Internal Testing of Synthesis Platform:
We routinely run tests of this platform to ensure the quality of the product.
Average Crude Purity of 10mers: ~86%
Average Crude Purity of 15mers: ~73%
Average Crude Purity of 20mers: ~61%
Purity of ACP peptide at different positions on a 96-well plate: ~92% +/- 2%

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Peptide Impurities

Customers often ask what other substances (impurities) are present in their peptide sample. This depends greatly on whether or not the sample was purified by reverse phase HPLC. The following table summarizes the difference between the two cases.

Impurities found in Non-Purified Peptides

• Deletion sequences
• Truncation sequences
• Incompletely deprotected sequences
• Sequences modified during cleavage (reattachment of protecting groups at other locations on the peptide)
• DTT (dithiothreitol)
• TFA (trifluoroacetic acid)
• Acetic acid
• Peptides that have undergone side reactions such as proline isomerization or isoaspartimide formation, etc.
  
  (Note that the impurities are both peptides and non-peptides.)

Impurities found in Purified Peptides

• Deletion sequences
• Truncation sequences
• Incompletely deprotected sequences
• Sequences modified during cleavage (reattachment of protecting groups at other locations on the peptide)
• TFA (trifluoroacetic acid)
• Peptides that have undergone side reactions such as proline isomerization or aspartimide formation etc.
  
  (Note that the impurities are mostly peptides with modified sequences, except for TFA salt.)

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Recommended Peptide Purity

Ig and >70%:For peptides used in the following applications:

• immunization and raising of polyclonal antiserum in animals
• performing an ELISA standard for measuring titers of antibodies

>80%: For peptides used in the following applications:

• non quantitative enzyme-substrate studies
• phosphorylation reactions
• non-quantitative peptide blocking studies for Western blotting,
  immunocytochemistry and in-vitro bio-assays
• coupling to chromatography resins for affinity purifications
• coating of tissue culture plates for cell attachment
• protein electrophoresis applications

>95%: For peptides used in the following applications:

• standard for quantitative ELISA and RIA protocols
• quantitative receptor-ligand interaction studies
• in vitro bioassays
• in vivo studies
• quantitative blocking and competition assays
• quantitative protease studies
• enzyme studies
• chromatography standard
• NMR studies
• monoclonal antibody production

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