Peptide N-Terminal Modification

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Creative Peptides has advanced peptide synthesis abilities and provides more than 40 types of N-terminal modifications to meet your needs in different research fields.

The necessary of peptide N-terminal modification

Although many of the most widely recognized post-translational modifications are characteristic of secretory or cell-surface proteins, most proteins, whatever their ultimate cellular desination, undergo some modification. For proteins synthesized completely within the cytoplasm, the earliest and most widespread are removal or modification of the N-terminal residue. In many proteins the N-terminal α-ammonium group (PK=8) undergoes secondary modification.

N-terminal modification reduces overall solubility of the peptide by reducing its overall charges. However, the stability of the peptide could also be increased because N-terminal modification generates a closer mimic of the native protein. Therefore, these modifications might increase the biological activity of a peptide and prevent degradation by enzymes.

Available N-terminal modifications

• Acetylation

Acetylation (N-terminus) will remove the positive charge and help peptides imitate its natural structure. In addition, this modification makes the resulting peptide more stable towards enzymatic degradation resulting from exopeptidases.

• Biotin

Biotin has a very strong affinity for streptavidin and avidin, so the biotinylation of peptides is an effective method for specifically binding peptides to streptavidin-coated surfaces.

Peptide biotinylation can be performed at the N-terminus or C-terminus. Biotin is directly coupled to the N-terminal primary amino group. Biotin-labeled peptides are commonly used in immunoassays, histocytochemistry, and fluorescence-based flow cytometry.

• Dansyl (5-(Dimethylamino) naphthalene-1-sulfonyl)

Dansyl labeled peptides are used in fluorescence-based assays. The excitation/emission wavelengths are about 342 nm/562 nm.

• DNP (2, 4-Dinitrophenyl)

DNP can be used as a quencher for MCA sometimes tryptophan. This modification can be attached to the N-terminus of the peptide, or it can be used as an internal modification via the lysine side chain. its excitation wavelength is 354-400 nm.

• Fatty Acid

Fatty acids bind to peptides at their N-terminus, increase their cell permeability, and help peptides bind to cell membranes. Peptide fatty acid modifications include caprylic acid (C8), capric acid (C10), lauric acid (C12), myristic acid (C14), palmitic acid (C16) or stearic acid (C18), etc.

• FITC (Fluoresceinisothiocyanate)

During peptide synthesis, the peptide can be directly conjugated to the fluorophore at the N-terminus (FITC always passes through the aminocaproic acid (Ahx) linker). For effective N-terminal labeling, a seven-atom aminohexanoyl spacer (NH2-CH2-CH2-CH2-CH2-CH2-COOH) is inserted between the fluorophore (fluorescein) and the N-terminal of the peptide.

The excitation/emission wavelengths are about 490 nm/520 nm.

• KLH, BSA

After peptide synthesis, the peptide can be coupled to two carrier proteins, KLH or BSA. The carrier protein can be conjugated to the N- or C-terminal of the peptide through the inserted N- or C-terminal cysteine. KLH or BSA-coupled peptides are mainly used for immunization and can significantly increase the cell-mediated immune response.

• MCA (7-Methoxycoumarinyl-4-acetyl)

7-Methoxycoumarin labeled peptides in protein-protein interaction and application localization. The excitation/emission wavelengths are about 325 nm/392 nm.

• Palmytoyl

The cysteine in the peptide can be palmitoylated, thereby increasing its cell permeability and helping the peptide bind to the cell membrane.

Creative Peptides is specialized in the custom synthesis of N-terminal modification peptides, providing a confidential and efficient service at competitive prices. Every step of peptide synthesis is subject to Creative Peptides' stringent quality control.

Typical delivery specifications include

• HPLC chromatogram
• Mass spec analysis
• Synthesis report
• Certificate of analyses

References

1. Dixon, H. B. F. N-terminal modification of proteins—a review. Journal of protein chemistry. 1984; 3(1):99-108.
2. Obermeyer, A. C., Jarman, J. B., & Francis, M. B. N-terminal modification of proteins with o-aminophenols. Journal of the American Chemical Society. 2014; 136(27):9572-9579.
3. Laurichesse, S., & Avérous, L. Chemical modification of lignins: Towards biobased polymers. Progress in Polymer Science. 2014; 39(7):1266-1290.