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Home » Peptide Services » Peptide Modifications

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
    BSA conjugation on N terminal -NH2 KLH conjugation on N terminal -NH2 OVA conjugation on N terminal -NH2 Acetylation
    Biotin Biotin-Ahx 5-FAM 5-FAM-Ahx
    6-FAM 6-FAM-Ahx 2-Abz 4-Abz
    Cy3 Cy5 Cy5.5 Cy7
    DABCYL Dansyl Dansyl-Ahx FITC-Ahx
    FITC-PEG2 5-TMR 6-TMR Rhodamine B
    MCA 3-Maleimide 6-Maleimide SMCC
    Acryl Alloc Benzoyl CBZ
    Fmoc Br-Ac Cl-Ac Aminooxy
    DOTA NOTA 1-Nap 2-Nap
    Succinylation Glutaric acid Butyric acid,C4 Hexanoic acid,C6
    Octanoic acid,C8 Nonanoic acid,C9 Decanoic acid,C10 Lauric acid,C12
    Myristic acid,C14 Palmitic acid,C16 Stearic acid,C18 Arachidic acid,C20
    L-Lactic acid D-Lactic acid (R)-Lipoic acid 2-Mercaptoacetic acid
    2-Azidoacetic acid 4-Azidobutyric acid 6-Azidohexanoic acid Propiolic acid
    5-Hexynoicacid Trans-Cinnamic acid Trans-Crotonic acid DBCO
    Methyltetrazine TCO
  • C-terminal modifications
    Amidation Alcohol
    AMC Bzl
    Cysteamide EDA-Biotin
    Ester (OEt) Ester (OMe)
    Glu(EDANS) Hydrazine
    MPAA NHEt
    Nhisopen NHMe
    TBzl p-Nitroanilide
    Tyr (3-NO2) BSA conjugation on C terminal -COOH
    KLH conjugation on C terminal -COOH OVA conjugation on C terminal -COOH
  • Special amino acids
  • Stable isotope labeled peptides
    {Arg(13C6,15N4)}
    {Ile(13C6,15N)}
    {Leu(13C6,15N)}
    {Lys(13C6,15N2)}
    {Phe(13C9,15N)}
    {Pro(13C5,15N)}
    {Val(13C5,15N)}
  • Fluorescent peptide modifications/FRET pairs
    2-Abz (N-Terminal) FITC-Ahx (N-Terminal)
    4-Abz (N-Terminal) FITC-PEG2 (N-Terminal)
    5-FAM (N-Terminal) MCA (N-Terminal)
    5-FAM-Ahx (N-Terminal) Rhodamine B (N-Terminal)
    6-FAM (N-Terminal) AMC (C-Terminal)
    6-FAM-Ahx (N-Terminal) {ACC}
    (7-Aminocoumarin-4-Acetic acid)
    5-TMR (N-Terminal) MCA/Lys(DNP)
    6-TMR (N-Terminal) 2-Abz/Lys(DNP)
    Cy3 (N-Terminal) 4-Abz/Lys(DNP)
    Cy5 (N-Terminal) 2-Abz/Tyr(3-NO2)
    Cy5.5 (N-Terminal) 4-Abz/Tyr(3-NO2)
    Cy7 (N-Terminal) DABCYL/Glu(EDANS)
    Dansyl (N-Terminal) DABCYL/EDANS
    Dansyl-Ahx (N-Terminal)
  • Peptide conjugates
    BSA (-COOH of C terminal)
    BSA (-NH2 of N terminal)
    BSA Conjugation on cysteine
    KLH (-COOH of C terminal)
    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) {PEG1}
    NH2-(PEG)1-CH2COOH    		 Head to tail amide cyclic Random Disulfide Bridge Dimer ( Inter-Disulfide bridge)
    MAPS Asymmetric 4 branches (C-Terminal) {PEG1-propionic acid}
    NH2-PEG1-CH2CH2COOH    		 Amide cyclic (Side chain) Mono Disulfide bridge
    MAPS Asymmetric 8 branches (C-Terminal) {PEG2}
    NH2-(PEG)2-CH2COOH    		 Stapled peptide(S5/S5) Double Disulfide bridge
    　 {PEG3}
    NH2-(PEG)3-CH2CH2COOH     		Stapled peptide(R8/S5) Triple Disulfide Bridge
    {PEG4}
    NH2-(PEG)4-CH2CH2COOH    		 Mono Thioether Bridge
    {PEG5}
    NH2-(PEG)5-CH2CH2COOH    		 Thioester (C-terminal)
    {PEG6}
    NH2-(PEG)6-CH2CH2COOH    		 Amide cyclic (Head to side chain)
    {PEG8}
    NH2-(PEG)8-CH2CH2COOH    		 Amide cyclic (Side chain to tail)
    {PEG11}
    NH2-(PEG)11-CH2COOH
    {PEG12}
    NH2-(PEG)12-CH2CH2COOH
  • Peptoid

    Key Features (Peptoid VS. Peptide)

    • More stable: Peptoids are less susceptible to degradation in vivo than peptides.
    • More choices: Peptoids are well suited for combinatorial approaches to drug discovery because large libraries can be synthesized easily from readily available primary amines.
    • More cost-effective and time-efficient: Major advances in screening methodology have allowed peptoid libraries of hundreds of thousands of compounds to be mined inexpensively and quickly for highly specific protein-binding.
    • Higher market potential: The features of peptoids make them a class of pharmacological agents with great potential.

    Service Specifications

    Peptoid Synthesis(Cat. No.: SC1559)

    • 20 different residues available, more in development
    • Peptoid length up to 20 residues
    • Peptoid purity from crude to ≥98%
    • Peptoid quantity up to 500 mg
    • Available modifications: Acetylation, Amidation, Biotin, FAM, FITC, TMR labeling
    • MS, HPLC, and COA provided for each peptoid
    • 2-6 weeks turnaround time, depending on the length and quantity of ordered peptoid

    Current Available Peptoid Side Chain

    Side Chain Name
    Code
    Structural Formula
    Methylamine
    {NAla}
    Methylamine Structural Formula
    Ethylamine
    {NAbu}
    Ethylamine Structural Formula
    n-propylamine
    {Nnpa}
    n-propylamine Structural Formula
    n-butylamine
    {Nnba}
    n-butylamine
    Isopropylamine
    {NVal}
    Isopropylamine Structural Formula
    Sec-butylamine
    {NIle}
    Sec-butylamine Structural Formula
    (S)-(+)-Sec-butylamine
    {(S)-NIle}
    (S)-(+)-Sec-butylamine
    (R)-(-)-Sec-butylamine
    {(R)-NIle}
    (R)-(-)-Sec-butylamine
    Isobutylamine
    {NLeu}
    Isobutylamine
    Benzylamine
    {NPhe}
    Benzylamine
    β-phenylethylamine
    {NPea}
    β-phenylethylamine
    α-methylbenzylamine
    {Nmba}
    α-methylbenzylamine
    (S)-α-methylbenzylamine
    {(S)-Nmba}
    (S)-α-methylbenzylamine
    (R)-α-methylbenzylamine
    {(R)-Nmba}
    (R)-α-methylbenzylamine
    2-(methylthio)ethylamine
    {NMet}
    2-(methylthio)ethylamine
    3-Methoxypropylamine
    {Nmpa}
    3-Methoxypropylamine
    1,4-Butylenediamine
    {NLys}
    1,4-Butylenediamine
    4-methoxyphenethylamine
    {Nmpe}
    4-methoxyphenethylamine
    3,4-Dimethoxybenzylamine
    {Ndmb}
    3,4-Dimethoxybenzylamine
    Tetrahydrofurfurylamine
    {Nffa}
    Tetrahydrofurfurylamine
    (S)-(+)-Tetrahydrofurfurylamine
    {(S)-Nffa}
    (S)-(+)-Tetrahydrofurfurylamine
    (R)-(-)-Tetrahydrofurfurylamine
    {(R)-Nffa}
    (R)-(-)-Tetrahydrofurfurylamine
    Piperonylamine
    {Npip}
    Piperonylamine
    4-(2-Aminoethyl)benzenesulfonamide
    {Nbsa}
    4-(2-Aminoethyl)benzenesulfonamide
    Tert-butylamine
    {Ntbu}
    Tert-butylamine
    Diisopropylamine
    {Ndip}
    N-terminal only
    Diisopropylamine
    Tryptamine
    {NHtrp}
    Tryptamine
    1H-Indole-3-methanamine
    {NTrp}
    1H-Indole-3-methanamine
    Cysteamine
    {NHcys}
    Cysteamine
    4-Hydroxybenzylamine
    {NTyr}
    4-Hydroxybenzylamine
    Histamine
    {NHhis}
    Histamine
    Glycine
    {NAsp}
    Glycine
    Glycinamide
    {NAsn}
    Glycinamide
    Beta-Alanine
    {NGlu}
    Beta-Alanine
    Beta-alanine amide
    {NGln}
    Beta-alanine amide

    Delivery Specifications

    The typical delivery package consists of lyophilized peptoids of required sequence, purity, quantity and associated QC reports. Every step of peptoid synthesis is subject to GenScript's stringent quality control.

* 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,please contact [email protected] for support.

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Peptide Modification Basics

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.

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, and 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 larger carrier proteins, such as bovine serum albumin (BSA), ovalbumin (OVA), or keyhole limpet hemocyanin (KLH). KLH is advantageous because it does not interfere with ELISA or western blotting, as it is not used as a blocking reagent. A common 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 for linkage.

Note: KLH is a large aggregating protein (MW = 4×10⁵ to 1×10⁷) with limited water solubility, which gives solutions a cloudy appearance. However, this does not affect immunogenicity, and the turbid solution can still be used for immunizations. For shipments, peptides are sent as solutions chilled with blue ice if precipitates form after conjugation.

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Case Study

  • Fluorescent Labeled Peptides

  • Click Peptides

  • Peptoid

Fluorescent Modification Case studies

Fluorescent peptide labels have numerous research applications, and GenScript has extensive experience synthesizing peptides with a variety of modifications.

Case Study 1

Sequence: LYRLGLGH
Modification: MCA/DNP
Quantity: 1-4 mg

Required purity Estimated Turnaround time Actual purity Actual turnaround time
>98%
17 days
99.563%
14 days

Click here to view HPLC results »

Fluorescent Modification Case study 1 HPLC results

Click here to view MS results »

Fluorescent Modification Case study 1 MS results

Case Study 2

Sequence: IKDLSKEERLWEVQRILTALKRKLREA
Modification: 5-FAM (N-terminal)
Quantity: 10-14 mg

Required purity Estimated Turnaround time Actual purity Actual turnaround time
>98%
23 days
99.10%
13 days

Click here to view HPLC results »

Fluorescent Modification Case study 2 HPLC results

Click here to view MS results »

Fluorescent Modification Case study 2 MS results

Case Study 3

Sequence: RAKWNNTLKQIASK
Modification: FITC-Ahx (N-terminal)
Quantity: 5-9 mg

Required purity Estimated Turnaround time Actual purity Actual turnaround time
>98%
17 days
99.81%
5 days

Click here to view HPLC results »

Fluorescent Modification Case study 3 HPLC results

Click here to view MS results »

Fluorescent Modification Case study 3 MS results

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