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Peptide Modifications

Over 300 modifications; Free amidation and acetylation

Includes Biotin, FITC, PEGylation, methylation, disulfide bonds

KLH, BSA, OVA conjugations

Custom Peptide Modifications

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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} NH₂-(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} NH₂-(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} NH₂-(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} NH₂-(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} NH₂-(PEG)₂-CH₂COOH		Mono Disulfide bridge	Succinylation
	{PEG6} NH₂-(PEG)₆-CH₂CH₂COOH		Triple Disulfide Bridge	Me
	{PEG11} NH₂-(PEG)₁₁-CH₂COOH			p-Nitroanilide
	{PEG12} NH₂-(PEG)₁₂-CH₂CH₂COOH			p-Nitroanilide

1. 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.

2. 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.

3. 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.

4. 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.

See more modifications...

5. 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.

6. 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.

7. 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.

8. 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.

9. 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.

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.

Quotations and Ordering

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For quotations, please use our Secure Instant Online Quotation/Order system. However, you may also contact us by email, phone (1-732-885-9188), fax (1-732-210-0262), or via our Secure Messaging System.

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