If the peptide is from an internal sequence of a protein, terminal amidation (C-terminus) or acetylation (N-terminus) will remove its charge and help it imitate its natural structure (amide, CONH2). In addition, this modification makes the resulting peptide more stable towards enzymatic degradation resulting from exopeptidases.
For C-terminal labeling of biotin, a Lys residue is added to the C-terminus of the peptide. Biotin is then attached to the lysine side chain via amide bond. The positive charge of the lysine is then removed.
Fluorescein isothiocyanate (FITC) is an activated precursor used for fluorescein labeling. For efficient N-terminal labeling, a seven-atom aminohexanoyl spacer (NH2-CH2-CH2-CH2-CH2-CH2-COOH) is inserted between the fluorophore (fluoroscein) and the N-terminus of the peptide.
Peptide cyclization can be achieved through creating disulfide bridges between cysteine residues on the peptide. This is a challenging practice for peptide containing multiple cysteine residues due to random formations of disulfide bridges between them. GenScript is able to build disulfide bridges between cysteine at specified positions. We are able to introduce up to three customized disulfide bridges on one peptide.
Phosphopeptides can assist in the investigation of the influences of phosphorylation on peptides and protein structure and in the understanding of regulatory processes mediated by protein kinases. GenScript has successfully synthesized numerous serine-, threonine-, and tyrosine-phosphopeptides. For peptides containing one or more of these hydroxy-amino acids, selective phosphorylation can be achieved by orthogonal protection or by Fmoc-protected phosphorylated amino acids.
The methylation of proteins has been established as an important modification that helps regulate cellular functions such as transcription, cell division, and cell differentiation. Post-translational N-methylation usually occurs on lysine or arginine sidechains. Peptides that represent methylated proteins are useful for protein-protein interaction studies or structural determination by x-ray crystallography. GenScript can synthesize peptides containing mono-, di-, and tri-methylated lysines at >98% purity, as well as other methylation combinations.
PEGylation is the covalent conjugation of macromolecules (antibody, peptide, etc.) with polyethylene glycol (PEG), polymers that are nonionic, nontoxic, biocompatible and highly hydrophilic. The PEGylated macromolecules have enhanced therapeutic properties due to their increased solubility (for hydrophobic drugs) and bioavailability, masked antigenicity for minimum immune response in host, prolonged circulatory time within host through reduced renal clearance.
For NMR measurement, we can label peptides with stable nonradioactive isotopes. Peptides labeled with 2H, 15N, 13C, or both 15N and 13C can be synthesized for convenient detection in research. Please submit your sequence and request for a customized labeling of your peptides.
Multiple antigen peptide application is one potent way to produce high-titer anti-peptide antibodies and synthetic peptide vaccines. This system utilizes the α- and ε-amino groups of lysine to form a backbone to which multiple peptide chains can be attached. Depending on the number of lysine tiers, different numbers of peptide branches can be synthesized. This eliminates the need to conjugate the antigen to a protein carrier.
Peptide antigens are often too small to generate significant immune responses on their own. To solve this problem, these peptides are conjugated to bigger carrier proteins, such as bovine serum albumin (BSA), ovalbumin, or keyhole limpet hemocyanin (KLH). One of the advantages of KLH is that it does not interfere with ELISA or western blotting because it is not used as a blocking reagent. One common means of conjugation method is the maleimide method, which couples the cysteine residue of the peptide to the carrier protein. To perform this conjugation, one cysteine residue is added to the N- or C-terminus of the peptide so that it may be linked to the carrier protein.
Note: KLH is a large (MW = 4*105 to 1*107) aggregating protein. Because of its size and structure, its solubility in water is often limited, giving solutions and mixtures a cloudy appearance. This does not affect immunogenicity and the turbid solution can be used for immunizations. To avoid further confusion, we'll ship the peptides as solutions chilled with blue ice if precipitates appear after conjugation.
All peptide synthesis is subject to GenScript's stringent quality control. The typical delivery consists of lyophilized peptide of the required sequence, purity, and quantity and associated QC reports.
GenScript can synthesize peptides with up to 3 disulfide bonds. However, the synthesis of 3-disulfide peptides is extremely difficult and random cyclization is recommended if possible.
The third singular cysteine will induce ring-opening in a built cysteine bridge and the molecule will be not stable. The production is difficult and needs to be evaluated by PT team.
Please kindly refer to the below table
| Name | Material | Material’s CAS | Excitation (nM) | Emission (nM) | Emission color | Position |
|---|---|---|---|---|---|---|
| MCA | 62935-72-2 | 328 | 393 | Blue | N-terminal | |
| Abz | 150-13-0 | 320 | 420 | Blue | N-terminal | |
| AMC | 167690-53-1 | 360 - 380 | 440 - 460 | Blue | C-terminal | |
| EDANS | 50402-56-7 | 340 | 490 | C-terminal | ||
| Dansyl | Dansyl | 605-65-2 | 342 | 562 | Green | N-terminal |
| FITC-Ahx | 3326-32-7 | 494 | 521 | Green | N-terminal | |
| FAM | 5-Carboxyfluorescein (5-FAM) | 76823-03-5 | 495 | 520 | Green | N-terminal |
| 5-TMR | 5-TAMRA(5-TMR) | 91809-66-4 | 542 | 568 | Orange | N-terminal |
| Cy3 | Sulfo-Cy3-NHS | 1518643-34-9 | 555 | 570 | Yellow | N-terminal |
| Sulfo-Cy3-Mal | 1656990-68-9 | N-terminal | ||||
| Cy5 | Sulfo-Cy5-NHS | 2230212-27-6 | 646 | 662 | Red | N-terminal |
| Sulfo-Cy5-Mal | 2242791-82-6 | N-terminal | ||||
| Cy5.5 | Sulfo-Cy5.5-NHS | 673 | 707 | Near-infrared | N-terminal | |
| Sulfo-Cy5.5-Mal | N-terminal | |||||
| Cy7 | Sulfo-Cy7-NHS | 1603861-95-5 | 750 | 773 | Near-infrared | N-terminal |
| Sulfo-Cy7-Mal | 2183440-60-8 | N-terminal |
We synthesize the Fret pairs in the below table
| Donor | Acceptor | ||||
|---|---|---|---|---|---|
| Name | Excitation (nm) | Emission (nm) | Name | Excitation (nm) | Emission (nm) |
| Cy2 | 490 | 510 | Cy3 | 555 | 570 |
| FAM | 495 | 520 | Cy3 | 555 | 570 |
| FAM | 495 | 520 | Cy5 | 646 | 662 |
| Cy3 | 555 | 570 | Cy5 | 646 | 662 |
| EDANS | 335 | 493 | DABCYL | 453 | - |
| Glu(EDANS)-NH2 | 335 | 493 | DABCYL | 453 | - |
| MCA | 328 | 393 | DNP | 348 | - |
| Abz | 330 | 420 | DNP | 348 | - |
| Trp | 280 | 360 | DNP | 348 | - |
| Abz | 330 | 420 | Tyr (3-NO2) | 360 | - |
If a FITC need to be modified on the N-terminal of the peptide, a linker (Ahx is 6-aminocaproic acid) should be added. If a FITC is modified on the N-terminal amino group directly without a linker, the Edman degradation reaction occurs in the cleavage process.
Yes, we can make branched peptides for you. Usually, the branched peptide should not be too long, 5-10mer would be fine. Our branched peptide is made through Lysine's side chain. We need to evaluate the sequences, if you would like to add two branches onto one original peptide.
We recommend that you position the phosphorylated residue no more than 10 residues away from the N-terminus because the coupling efficiency of residues following a phosphorylated residue is significantly reduced
Unfortunately, we can't make such a modification at present time. We can perform Ser, Thr, and Tyr phosphorylation modification.
Capping will make peptide appear more like native protein. The N terminus can be capped with an acetyl group and C terminus with an amide group.
PEGylation adds polyethylene glycol polymer to target molecules through covalent attachments. PEGylation effectively enhances the peptides' therapeutic properties by masking them from the host's immune system, increasing their solubility (for hydrophobic drug GenScript) and bioavailability. It can also prolong the peptides circulatory time within the host through reduced renal clearance.
Yes, it can be added in a format of a special amino acid Lys(Biotin), to label it at the side chain of Lys. To add a linker, we could make it as peptide-Ahx-Lys(Biotin).
We provide 13C and 15N isotopic labeled peptide. , , , , and are commonly provided isotopic amino acids. Other a.as can be provided according to your demands, but there would be longer the TAT since we need to order raw materials and prices also varies.
Yes, we can. There are three methods used to finish protein conjugated peptides. GA method uses an amino group for conjugation, the EDC method uses a carboxyl group for conjugation and the MBS method uses a sulfhydryl group for conjugation.
Yes. Peptoids, or poly-N-substituted glycines, are a class of peptidomimetics whose side chains are appended to the nitrogen atom of the peptide backbone rather than to the α-carbon (as they are in amino acids). Please check following link for reference. https://www.genscript.com/peptoid_synthesis.html
We can provide mini-PEG with two size, which is composed with 2 molecular with 152 Da and 3 molecular with 190 Da respectively. The size we use is depends on the your request. Mini-PEG 2(152 Da) is frequently used.
Generally, Peptides which are less than 6 amino acids and/or very hydrophobic may be difficult to precipitate. An alternative work-up is to evaporate the ether, dissolve the sample in 10% aqueous acetic acid, and extract the organic scavengers and byproducts with chloroform.
If FITC is directly modified at the n-terminal amino group, the Edman degradation reaction occurs in the cleavage process, as shown in the following figure. Edman degradation is the process of determining the sequence of amino acid residues from the N terminal free of a polypeptide chain. N-terminal amino acid residues were modified by phenyl isothiocyanate, and then the modified residues were cut from the polypeptide chain (the amino acids directly linked to PITC), which were identified by chromatography, and the remaining polypeptide chains (with one less residue) were recycled for the next degradation cycle.
Yes, we can handle such peptides. The synthesis of such peptides is similar to regular peptide synthesis, but due to the low coupling efficiency, the turnaround time will be several days longer than the regular amino acids. The Price is closely related to its specific sequence, we are willing to evaluate it with its specific sequence.
At present, we provide peptides service with alkyne and Azide. We can provide {Lys(N3)} and Propargylglycine.
{Lys(N3)}
Propargylglycine
We had produced the peptides containing 25 consecutive Arg residues. If you'd like to, we can have a try, but it is hard to ensure success.
Typically, the peptide should be white without any modifications. However, if the peptide undergoes oxidation during transportation, it may appear pink or yellow. If the peptide without modifications is not white upon receipt, please contact us.
Q at N terminal of peptide is not stable in acidic condition (such as purification and lyophilized) and could undergo cyclization reaction to form pGlu.
To to avoid such as side reaction, N-terminus acetylation is recommended.
Other solutions are 1) Remove "Q" from N-terminus 2) Add another amino acid in front of "Q".
Please use the following website: http://www.molbiol.ru/eng/scripts/01_17.html
GenScript can provide multiple modifications, please kindly find the full names and abbreviations of the modifications in the link below.
https://www.genscript.com/peptide_modification.html
