Please refer to the corresponding frequently asked questions (FAQs) below.
If you can not find the question you are looking for, please contact our customer support team: firstname.lastname@example.org
Which types of SpikeTides™ are available?
proteotypic peptides with c-terminal Lys or Arg residue.
proteotypic peptides with additional c-terminal tag. SpikeTides T need to undergo tryptic digestion to release the native proteotypic peptide.</br>
SpikeTides™ T labeled with stable isotopes carrying an additional c-terminal tryptic tag. SpikeTides TL need to undergo tryptic digestion to release the heavy labeled native proteotypic peptide. </br>
SpikeTides T provided with information on absolute quantity for each peptide. SpikeTides™ TQ need to undergo tryptic digestion to release respective proteotypic peptide. </br>
SpikeTides™ T fully quantified and labeled with stable isotopes carrying an additional c-terminal tryptic tag.
SpikeTides™ TQL need to undergo tryptic digestion to release respective proteotypic peptide.
Which type of SpikeTides™ is the best one for my application?
SpikeTides™ are light proteotypic peptides intended for optimization and validation of multiplexed SRM assays.
SpikeTides™ L are isotopically labeled proteotypic peptides with C-terminal heavy Arg or Lys for development of SRM assays and relative quantification of proteins using a single product.
SpikeTides™ TQ are light and quantified proteotypic peptides that can be used for quantification of isotopically labeled proteins in biological samples (e.g SILAC).
SpikeTides™ TQL are isotopically labeled and absolutely quantified proteotypic peptides with C-terminal heavy Arg or Lys for absolute quantification of proteins in biological samples.
Why is the tag necessary?
The tag is necessary for realizing the peptide synthesis for heavy labeled peptides.
In addition, the tag carries a moiety enabling the quantification of the target peptide during HPLC-runs using specific wavelengths.
The tag is optimized to enable efficient cleavage using standard proteases like trypsin.
After cleavage, the proteotypic peptide with the native C-terminus is available for the MRM assay.
Do you have a specific protocol used for the application of SpikeTides™ with or without tag?
JPT Peptide Technologies provides a detailed protocol together with every SpikeTides™ library including plate layout and sequence list in Excel-format.
Are the termini of the peptides modified in any way?
As necessary for proteotypic peptides, the N-termini are free, the C-termini are acidic.
What amount of peptide is in each well?
For the SpikeTides™, SpikeTides™ T and SpikeTides™ TL, a rough estimation of the peptide amount is given in the product documentation.
The estimation of peptide amount is based on the determination of the amount of coupled amino acid in the last step.
For the quantified SpikeTides™ TQ and SpikeTides™ TQL, the synthesized peptides is aliquoted in 5x1nmol fractions.
Quantification is based on HPLC-MS analytics and UV read-out of the Quantification-tag.
What information will be provided?
An Excel-Spreadsheet will be provided giving all information concerning peptide sequence, sequence ID (if given), synthesis batch number and corresponding well in the microtiterplate/96 tubes rack.
How much enzyme is needed for the cleavage of the tagged SpikeTides™?
The cleavage of the SpikeTides™ can be performed in the same assay solution as the tryptic digest of the target protein takes place.
How do I know that the cleavage of peptide / tag was succesfull?
JPT Peptide Technologies validated the cleavage efficency for many different peptide surroundings.
The efficiency of the cleavage can be checked by doing HPLC-runs after the cleavage was performed.
The signal of the cleaved tag should bevisible at a retention time of 0 to 0.5min (C18, 3µ, 20x2mm, 1ml/min flowrate, 6 minute gradient, 5% to 95% Acetonitril water) and should light up when analyzed at 350nm.
Uncleaved peptide /tag will have a signal at higher retention times (for examples and details about these validation steps, please contact our customer support at email@example.com).
What is the chemical stability of the peptides?
As long as the peptides are freeze dried and kept at low temperature, the stability is very good.
Once thawed and dissolved in buffer solution, JPT Peptide Technologies recommends to perform the assay without further delay to avoid degradation of the peptides.
How are the plates shipped and how should the plates be stored upon arrival?
The plates or micronic racks are shipped at room temperature.
For long-term storage JPT Peptide Technologies recommends to keep the plates /racks sealed at 4°C.
Do I need special reagents/chemicals to perform the assay?
A sample of protease trypsin is required to cleave the tag.
Potentially, other required chemicals are described in the protocol and are dependent on the modifications of the library ordered.
Is there any other modification I need to consider in respect to my desired peptide?
JPT Peptide Technologies recommends to exchange all Cysteine residues by alkylated Cysteine and all Methione residues by sulfoxided Methionine.
What other delivery options are there?
JPT Peptide Technologies will be able to ship the peptides in different formats, plates and tubes.
Default shipping formats are freeze dried peptides in sealed 96 wellplates (SpikeTides™, SpikeTides™ T and SpikeTides™ TL) or freeze dried aliquoted peptides in sealed 96 tube micronic racks (SpikeTides™ TQ and SpikeTides™ TQL).
Both plates or racks are filled row-wise from the upper left corner.
Changes in shipping formats can be discussed and evaluated with our customer support but might be subject to additional pricing.