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FAQ What type of peptide chemistry and purification method does Pi Proteomics use? What modifications can you perform? What Quality Control documentation do you supply? Do you guarantee the peptides? How difficult is it to Synthesize a Custom Peptide? What is the purpose of having N-acetylation and C-amidation? What is the difference between Biotin and Biotin-LC? If I order a cyclized peptide containing Trp, is there a possibility that the Trp will get oxidized? How do you ship the peptide(s) I ordered? How should I store the peptide(s)? How are the peptides supplied to me? What is the difference between “Gross Weight” and “Net Weight”? What does the purity mean on the HPLC report? Do I need to add a cysteine to my peptide for conjugation? Does Pi Proteomics conjugate peptides for antibody production? Is the animal facility approved by NIH and the FDA? What peptide purity is recommended for antibody production? What does SPF (Specific Pathogen Free) rabbits mean?
FAQ Answers What type of peptide chemistry and purification method does Pi Proteomics use? Pi Proteomics uses solid phase Fmoc chemistry. We use either the PTI symphony, PTI PS3, CEM Liberty, ABI 433, 9050 or ACT 396 for peptide synthesis. All of the peptides are for “Research Use Only”. During peptide purification, we use ACN, 2-Propanol and MeOH to purify the crude peptides using RP-HPLC techniques.
What modifications can you perform?
We can perform a host of modifications to your peptide. Here is a sample of the peptide modifications we perform on a routine basis. D-amino acids, phosphorylation, biotinylation, FITC, TAMRA, 5,6 FAM, Acetylated Lysine, Methylated Arginine, Methlyated Lysine, Hydroxy Proline, Beta Alanine, Myristic acid, 3-nitro Tyrosine, Octanoic acid, Pyro Glutamic acid, Ahx, citrulline, MAP and cyclization, stable isotope amino acids, and etc.
What Quality Control documentation do you supply? With all purified peptides, you will receive a Certificate of Analysis, a mass spectrometry report and a HPLC analytical report. With all “crude” purity peptides, you will receive a Certificate of Analysis and a Mass Spectrometry report. An Amino Acid Analysis (AAA) is available, upon request at an additional cost. AAA is used to determine peptide content and composition. Peptide Sequencing is available, upon request at an additional cost. Peptide Sequencing is used to validate that the proper peptide sequence was synthesized.
Do you guarantee the peptides? At Pi Proteomics, we guarantee the quality of our purified peptides. All purified peptides will be delivered with the following reports to validate the peptide: a mass spec (MALDI-Tof or Electrospray), analytical HPLC (with gradient, reagents, flow rate) and a Certificate of Analysis. We believe that if you use high quality peptides from Pi Proteomics you will see an increase in successful experiments and a decrease in research time. Pi Proteomics Custom Peptide Guarantee: If the peptide does not meet your purity requirements, Pi Proteomics will remanufacture the peptide at no cost to you. How difficult is it to Synthesize a Custom Peptide? Peptides, unlike oligonucleotides, which can be produced quickly and predictably, are often difficult to synthesize due to their many chemically different residues. Modern Fmoc synthesis chemistry and improvements in automated instrumentation have greatly improved the efficiency, cost and quality of resulting peptides, but expert chemists are still required for adequate problem solving, synthesis and purification method determination. We have >99% success rate.
What is the purpose of having N-acetylation and C-amidation? These terminal modifications mimic charges found in some hydrophobic, internally isolated protein sequences, or inter-membrane proteins of a native environment.
What is the difference between Biotin and Biotin-LC? LC (long chain) biotin is a biotin molecule spaced away from the peptide with the six carbon spacer -amino-hexanoic acid.
If I order a cyclized peptide containing Trp, is there a possibility that the Trp will get oxidized? Most of our cyclized peptides are oxidized while the Trp is still protected which insures the Trp remains in its reduced form. The peptide is purified after the cyclization, which eliminates any oxidized Trp. Oxidation of any of the peptide residues can be seen as a mass gain of 16 Amu.
How do you ship the peptide(s) I ordered? We ship all peptides by FedEx Standard Overnight at room temperature. However, we can ship on your FedEx account at not additional cost to you..
How should I store the peptide(s)? We recommend keeping the vial capped at all times and add nitrogen or argon to the vial in order to blanket the peptide. The nitrogen or argon will help reduce the chances of oxidation of the following amino acids: cysteine, tryptophan, and methionine. For short term storage (1 week to 3 months) use a -200C freezer, for long term storage (3months +) use a -800C freezer. Try to avoid repeated freezing-thawing of the peptides. If peptide samples are needed frequently or periodically, we recommend making a series of aliquots from the stock peptide. Please see our “Storing and Solubilizing Peptides” Product Insert.
How are the peptides supplied to me? We ship all peptides lyophilized in a glass vial. The weight on the vial is the peptide gross weight.
What is the difference between “Gross Weight” and “Net Weight”? Unless other requested, all peptides are shipped according to its gross weight. Gross Weight is the actual weight of the lyophilized product. Gross Weight includes any impurities such as residual water and/or salts from the TFA counterions accumulated during the synthesis and purification processes. “Net Weight” is the amount of actual peptide present minus the impurities. In order to find “Net Weight”, an AAA must be performed.
What does the purity mean on the HPLC report?
The purity of the peptide is determined by HPLC analysis with detection at 220 nm. The purity of the peptide does not take into account water and salts that are usually present in the sample. Other contaminates found with the peptide can range from sequence deletion, truncation or incompletely deprotected sequences. The peptide’s purity is the amount of correct peptide relative to all analytes that absorb at 220 nm.
Do I need to add a cysteine to my peptide for conjugation? No, generally speaking. However, if the peptide sequence selected is at the terminal position of the n-term of the protein, a cysteine needs to be added to the c-term of the peptide for conjugation.
Does Pi Proteomics conjugate peptides for antibody production?
Yes, we can conjugate your peptides to KLH, BSA, OVA, THY, MAP for polyclonal or monoclonal antibody production.
Is the animal facility approved by NIH and the FDA? Yes, AAALAC - accredited, USDA Research Licensed, OPRR assured and managed under Good Manufacturing Practices. All protocols are IACUC reviewed.
What peptide purity is recommended for antibody production? Pi Proteomics recommends using >80% peptide purity for polyclonal antibody production. Although using a lower purity peptide will not affect antibody response, subsequent screening and purification results will be improved with higher purity peptides. For Monoclonal Antibody production, >95% purity is recommended.
What does SPF (Specific Pathogen Free) rabbits mean? We use a platform of parasites, protozoa, viruses, and bacteria to screen for to ensure that the most common illnesses found in conventional colonies, including pasteurella and bordetella, are not present in our colonies. |
