Overview

The peptide modification services at GenScript offer a wide range of modifications to meet any research need. These modifications can improve overall peptide stability, alter structure to better understand biological function, or enhance immunogenicity for antibody development and production. In addition to a variety of terminus and internal modifications, GenScript's services include peptide labeling and conjugations for imaging and detection needs.

For a list of our available modifications, select the modification options below

  • N-terminal modifications
    5-FAM BSA (-NH2 of N terminal) Hexanoic acid PEN
    5-FAM-Ahx CBZ HYNIC Stearic acid
    Abz Dansyl KLH (-NH2 of N terminal) Succinylation
    Acetylation Dansyl-Ahx Lauric acid TMR
    Acryl Decanoic acid Lipoic acid  
    Alloc DTPA Maleimide  
    Benzoyl Fatty Acid MCA  
    Biotin FITC Myristoyl  
    Biotin-Ahx FITC-Ahx Octanoic acid  
    BOC Fmoc OVA (-NH2 of N terminal)  
    Br-Ac- Formylation Palmitoyl  
  • C-terminal modifications
    AFC MAPS Asymmetric 2 branches
    AMC MAPS Asymmetric 4 branches
    Amidation MAPS Asymmetric 8 branches
    BSA (-COOH of C terminal) Me
    Bzl NHEt
    Cysteamide NHisopen
    Ester (OEt) NHMe
    Ester (OMe) OSU
    Ester (OtBu) OVA (-COOH of C terminal)
    Ester (OTBzl) p-Nitroanilide
    KLH (-COOH of C terminal) tBu
  • Special amino acids
    {d-ALA}
    Alanine
    {NVA}
    Norvaline
    {pTYR}
    Phosphorylation (TYR)
    {Lys(biotin)}
    Biotin Lysine
    {D-2-Nal} {L-4-Pal} {Mini-PEG1} {PEG2}
    NH 2-(PEG)2-CH2COOH
    {d-ARG}
    Arginine
    {d-NVA}
    Norvaline
    {gamma-GLU}
    Gamma-GLU
    {Cys(Acm)}
    Cysteine (Acm)
    {D-3-Pal} {Lys(5-FAM)} {Met(O)}
    Methionine sulfoxide
    {PEG6}
    NH 2-(PEG)6-CH2CH2COOH
    {d-ASN}
    Asparagine
    {ORN}
    Ornithine
    {d-gamma-GLU}
    D-Gamma-GLU
    {Cys(tBu)}
    Cysteine (tBu)
    {D-4-F-Phe} {Lys(Dansyl)} {Met(O)2}
    Methionine sulfone
    {PEG11}
    NH 2-(PEG)11-CH2COOH
    {d-ASP}
    Aspartic Acid
    {d-ORN}
    Ornithine
    {CIT}
    Citrulline
    {d-1-NAL}
    (D) 1-Nal
    {D-4-I-Phe} {Lys(FITC)} {Cpg}
    Cyclopentylglycine
    {PEG12}
    NH 2-(PEG)12-CH2CH2COOH
    {d-CYS}
    Cysteine
    {PEN}
    Penicillamine
    {nme-ALA}
    N-methylated ALA
    {L-1-NAL}
    (L) 1-NAL
    {D-4-NO2-Phe} {Lys(Me)} {Pra}
    Propargylglycine
    Dab(Dnp)
    {d-GLU}
    Glutamic Acid
    {d-PEN}
    Penicillamine
    {nme-ILE}
    N-methylated Isoleucine
    {d-2-PAL}
    (D) 2-PAL
    {D-4-Pal} {Lys(Me2)} {Tic}
    1,2,3,4-Tetrahydroisoquin
    oline-3-carboxylic acid
    Dap(Dnp)
    {d-GLN}
    Glutamine
    {d-PHE}
    Phenylalanine
    {nme-LEU}
    N-methylated Leucine
    {L-2-PAL}
    (L) 2-PAL
    {D-Beta-Asp} {Lys(Me3)} {Sec}
    Selenocysteine
    Dpa
    {HCY}
    Homocysteine
    {d-PRO}
    Proline
    {nme-PHE}
    N-methylated Phenylalanine
    {d-4-CL-PHE}
    (D) 4-CL-PHE
    {D-Cha} {Lys(TMR)} {Se-Met}
    Selenomethionine
    Lys(Dde)
    {d-HIS}
    Histidine
    {d-SER}
    Serine
    {nme-VAL}
    N-methylated Valine
    {L-4-CL-PHE}
    (L) 4-CL-PHE
    {D-Chg} {NMe-Asp} {Lys(N3)}
    Azido-Lysine
    Lys(ivdde)
    {HSE}
    Homoserine
    {d-THR}
    Threonine
    {nme-SER}
    N-methylated Serine
    {ABU}
    Abu
    {D-Cit} {NMe-Glu} {Beta-HomoLeu}
    Beta-HomoLeucine
    Oic
    {d-HSE}
    Homoserine
    {d-TRP}
    Tryptophan
    {nme-THR}
    N-methylated Threonine
    {AIB}
    Aib
    {Dab} {NMe-Nle} {Cys(Cam)}
    Carboxyamidomethy
    lated Cysteine
    Pip
    {d-ILE}
    Isoleucine
    {d-TYR}
    Tyrosine
    {nme-TYR}
    N-methylated Tyrosine
    {MPA}
    Mpa
    {Dap} {NMe-Nva} {Arg(Me)}
    Methylation at the side chain of Arginine
    Tle
    {d-LEU}
    Leucine
    {d-VAL}
    Valine
    {alpha-ABA}
    Alpha Amino-Butyric Acid
    {HYP}
    Hydroxy Proline
    {L-2-Nal} {Phg} {ADMA}
    Arg(Me)2 asymmetrical
     
    {d-LYS}
    Lysine
    {pGLU}
    Pyroglutamate
    {Beta-Asp}
    Beta-ASP
    {Lys-Ac}
    Acetylation at the side chain
    {L-3-Pal} {Ser(octanoic-acid)} {SDMA}
    Arg(Me)2 symmetrical
     
    {d-MET}
    Methionine
    {Lys(Dnp)}
    Dinitrobenzylation (LYS)
    {Ac-LYS}
    Acetylation at alpha amine group
    {Cha} {L-4-F-Phe} {d-HCY}
    Homocysteine
    {Beta-Ala}
    Beta-Alanine
     
    {NLE}
    Norleucine
    {pTHR}
    Phosphorylation (THR)
    {2-Me-ALA}
    2-Methyl Alanine
    {Chg} {L-4-I-Phe} {d-pGLU}
    Pyroglutamate
    {GABA}
    4-Aminobutyric acid
     
    {d-NLE}
    Norleucine
    {pSER}
    Phosphorylation (SER)
    {nme-GLY}
    N-methylated Glycine
    {D-2-Me-Trp} {L-4-NO2-Phe} {nme-MET}
    N-methylated Methionine
    {Ahx}
    6-amino-hexanoic acid
     
  • Stable isotope labeled peptides
    Arg(13C6,15N4)
    Ile(13C6,15N)
    Leu(13C6,15N)
    Lys(13C6,15N2)
    Val(13C5,15N)
  • Fluorescent peptide modifications/FRET pairs
    1-Pyrenemethylamine HCL FITC (N-Terminal)
    5-FAM (N-Terminal) FITC-Ahx (N-Terminal)
    5-FAM-Ahx (N-Terminal) Glu(EDANS)-NH2
    Abz (N-Terminal) MCA (N-Terminal)
    Abz/DNP MCA/DNP
    Abz/Tyr (3-NO2) Quenched fluorescent peptide
    DABCYL Tyr (3-NO2)
    DABCYL/Glu(EDANS)-NH2 TMR
    Dansyl (N-Terminal) AMC
    Dansyl-Ahx (N-Terminal)  
    EDANS/DABCYL  
  • Peptide conjugates
    BSA (-COOH of C terminal)
    BSA Conjugation on cysteine
    KLH (-NH2 of N terminal)
    KLH Conjugation on cysteine
    OVA (-COOH of C terminal)
    OVA (-NH2 of N terminal)
    OVA Conjugation on cysteine
  • Other modifications (MAPS, PEGylation, cyclic modifications)
    MAPS PEGylation Cyclic modifications Disulfide Bridges Other
    MAPS Asymmetric 2 branches (C-Terminal) Mini-PEG1 Head to tail Cyclic Disulfide Bridge BOC
    MAPS Asymmetric 4 branches (C-Terminal) Mini-PEG2   Double Disulfide bridge tBu
    MAPS Asymmetric 8 branches (C-Terminal) {PEG2}
    NH 2-(PEG)2-CH2COOH
      Mono Disulfide bridge Succinylation
      {PEG6}
    NH 2-(PEG)6-CH2CH2COOH
      Triple Disulfide Bridge Me
    {PEG11}
    NH 2-(PEG)11-CH2COOH
    p-Nitroanilide
    {PEG12}
    NH 2-(PEG)12-CH2CH2COOH
    p-Nitroanilide
  • Available modifications for express peptide services

    Express peptide services consist of fast and rush peptide synthesis services(SC1845/SC1848), the available modifications for express peptide synthesis services are listed:

    N-terminal modifications

    BSA conjugation on N terminal –NH2 KLH conjugation on N terminal –NH2 OVA conjugation on N terminal –NH2
    5-FAM 5-FAM-Ahx Acetylation
    Biotin-Ahx Biotin-Ahx FITC-Ahx
    Succinylation

    C-terminal modifications

    BSA conjugation on C terminal –COOH KLH conjugation on C terminal –COOH
    OVA conjugation on C terminal –COOH Amidation

    Other modifications

    BSA conjugation on cysteine KLH conjugation on cysteine OVA conjugation on cysteine
    Amidation Cysteamide  

    Special amino acids

    {d-ALA}
    Alanine
    {d-ARG}
    Arginine
    {d-ASN}
    Asparagine
    {d-ASP}
    Aspartic Acid
    {d-CYS}
    Cysteine
    {d-GLU}
    Glutamic Acid
    {d-GLN}
    Glutamine
    {HCY}
    Homocysteine
    {d-HIS}
    Histidine
    {HSE}
    Homoserine
    {d-HSE}
    Homoserine
    {d-ILE}
    Isoleucine
    {d-LEU}
    Leucine
    {d-LYS}
    Lysine
    {d-MET}
    Methionine
    {NLE}
    Norleucine
    {d-NLE}
    Norleucine
    {NVA}
    Norvaline
    {d-NVA}
    Norvaline
    {ORN}
    Ornithine
    {d-ORN}
    Ornithine
    {PEN}
    Penicillamine
    {d-PEN}
    Penicillamine
    {d-PHE}
    Phenylalanine
    {d-PRO}
    Proline
    {d-SER}
    Serine
    {d-THR}
    Threonine
    {d-TRP}
    Tryptophan
    {d-TYR}
    Tyrosine
    {d-VAL}
    Valine
    {pGLU}
    Pyroglutamate
    {Lys(Dnp)}
    Dinitrobenzylation (LYS)
    {gamma-GLU}
    Gamma-GLU
    {d-gamma-GLU}
    D-Gamma-GLU
    {CIT}
    Citrulline
    {Ac-LYS}
    Acetylation at alpha amine group
    {Lys(biotin)}
    Biotin Lysine
    {d-1-NAL}
    (D) 1-Nal
    {L-1-NAL}
    (L) 1-NAL
    {d-2-PAL}
    (D) 2-PAL
    {L-2-PAL}
    {d-4-CL-PHE}
    {L-4-CL-PHE}
    {ABU}
    {AIB}
    {HYP}
    {Lys-Ac}
    {Cha}
    (L) 2-PAL (D) 4-CL-PHE (L) 4-CL-PHE Abu Aib Hydroxy Proline Acetylation at the side chain
    {Chg}
    {D-2-Nal}
    {D-3-Pal}
    {D-4-F-Phe}
    {D-4-I-Phe}
    {D-4-NO2-Phe}
    {D-4-Pal}
    {D-Cha}
    {D-Chg}
    {Dab}
    {Dap}
    {L-2-Nal}
    {L-3-Pal}
    {L-4-F-Phe}
    {L-4-I-Phe}
    {L-4-NO2-Phe}
    {L-4-Pal}
    {Phg}
    {d-HCY}
    Homocysteine
    {d-pGLU}
    Pyroglutamate
    {Beta-Ala}
    Beta-Alanine
    {GABA}
    4-Aminobutyric acid
    {Ahx}
    6-amino-hexanoic acid
    {Met(O)}
    Methionine sulfoxide
    {Met(O)2}
    Methionine sulfone
    {Cpg}
    Cyclopentylglycine
    {PEG2}
    NH2-(PEG)2-CH2COOH
    {PEG6}
    NH2-(PEG)6-CH2CH2COOH
    {PEG11}
    NH2-(PEG)11-CH2COOH
    {PEG12}
    NH2-(PEG)12-CH2CH2COOH
    {Lys(N3)}
    {Tic }

    Phosphorylation

    {pSER}
    {pTYR}
    {pTHR}

* For your convenience, modifications can easily be added when you request a quote online. If you don't find the modification you are looking for, feel free to your technical account manager for more information.

Learn more about Fatty Acid Conjugation

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Amidation and Acetylation

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.

Biotin and FITC

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.

Disulfide Bridge

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.

Phosphorylation

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.

Methylation

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

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.

Isotope Labeling

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.

MAPS

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.

BSA, KLH, OVA Conjugation

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.

Delivery Specifications

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.

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