Tetraglycine is an oligopeptide composed of four glycine residues and is commonly used as a simple, flexible peptide linker in biochemical and synthetic research. Its small size, neutral structure, and high conformational flexibility make it useful for spacing functional groups, modifying biomolecules, and designing peptide-based conjugates. Tetraglycine can also serve as a model peptide for studying peptide bond formation, enzymatic processing, and structure–activity relationships in short glycine-rich sequences. This peptide is widely applied in peptide synthesis, linker design, protein modification, chemical biology, and biomaterials research requiring a compact and flexible glycine-based spacer.
Product Name: Tetraglycine
Purity: 98%
Sequence: GGGG
CAS.NO.: 637-84-3
Chemical Formula: C8H14N4O5
Molar Mass: 246.22
Appearance: White to off-white Solid
Storage : Sealed storage, away from moisture and light, under nitrogen
SMILES: C(C(=O)NCC(=O)NCC(=O)NCC(=O)O)N
IUPACNAME: 2-[[2-[[2-[(2-aminoacetyl)amino]acetyl]amino]acetyl]amino]acetic acid
INCHIKEY: QMOQBVOBWVNSNO-UHFFFAOYSA-N
INCHI: InChI=1S/C8H14N4O5/c9-1-5(13)10-2-6(14)11-3-7(15)12-4-8(16)17/h1-4,9H2,(H,10,13)(H,11,14)(H,12,15)(H,16,17)
Current Research: Tetraglycine is a short oligopeptide composed of four glycine monomers, commonly represented as Gly-Gly-Gly-Gly or GGGG. Because glycine is the smallest amino acid and lacks a side chain beyond hydrogen, tetraglycine is highly flexible, compact, and structurally simple. These properties make it a useful building block in peptide chemistry, bioconjugation, protein engineering, enzymology, biomaterial research, and linker design. Although tetraglycine does not usually function as a bioactive signaling peptide by itself, it is widely valuable as a spacer, substrate motif, synthetic intermediate, and model peptide. A major application of tetraglycine is flexible linker design. In peptide and protein engineering, glycine-rich linkers are used to separate functional domains while minimizing steric interference. Tetraglycine provides a short and highly mobile spacer that can improve accessibility between two molecular components, such as a targeting peptide and payload, a protein domain and affinity tag, or a fluorophore and recognition motif. Compared with rigid or hydrophobic linkers, a glycine-only linker introduces minimal side-chain bulk and can preserve flexibility in compact constructs. Tetraglycine is also useful in bioconjugation research. Many conjugates require a short peptide spacer between a biomolecule and a functional group, such as biotin, fluorescent dye, drug payload, lipid, polymer, resin, nanoparticle, or affinity handle. A GGGG linker can reduce steric hindrance and improve presentation of the active motif. It may be incorporated into peptide–drug conjugates, antibody–drug conjugate model linkers, peptide probes, enzyme substrates, receptor ligands, and surface-functionalized biomaterials. In peptide synthesis, tetraglycine serves as a simple and reliable synthetic unit. Its small, uncharged residues make it useful for building peptide libraries, linker panels, and model substrates. Researchers may use tetraglycine-containing sequences to optimize coupling efficiency, purification, HPLC behavior, mass spectrometry detection, or terminal modification strategies. Because glycine-rich sequences are relatively neutral and flexible, tetraglycine is often chosen when the linker should not introduce strong charge, hydrophobicity, or secondary structure. Tetraglycine is also relevant to enzymology. Short glycine-rich peptides can serve as model substrates or spacer regions in protease, ligase, transpeptidase, and peptidase assays. In some protein modification systems, oligoglycine motifs participate in enzyme-mediated ligation or recognition. Tetraglycine may be used to study cleavage susceptibility, peptide bond formation, substrate flexibility, or steric effects in enzyme-catalyzed peptide processing. It can also be incorporated into longer substrates to separate a cleavage motif from a fluorescent, chromogenic, or affinity tag. In chemical biology, tetraglycine can support probe construction. For example, a tetraglycine spacer may be inserted between a binding peptide and a reporter group to improve probe performance. It may also be used in pull-down reagents, fluorescence probes, peptide arrays, immobilized ligands, and biosensor surfaces. When a recognition peptide is placed too close to a bulky tag or surface, binding can be reduced. A tetraglycine linker can provide enough spacing to improve target access while keeping the total construct short. Biomaterial research is another important use. Glycine-rich sequences are common in extracellular matrix proteins, silk-like materials, elastin-like peptides, and collagen-related structures. Although tetraglycine is much shorter than natural structural proteins, it can serve as a minimal flexible segment in synthetic biomaterials. Researchers may incorporate tetraglycine into hydrogels, peptide amphiphiles, surface coatings, scaffold-binding peptides, or matrix-mimetic materials to tune flexibility, spacing, and molecular presentation. Tetraglycine may also be used in drug delivery and nanoparticle functionalization. When targeting peptides or cell-penetrating peptides are attached directly to nanoparticle surfaces, steric crowding can reduce receptor binding or uptake. A short GGGG spacer can help project the functional peptide away from the carrier surface. This can improve accessibility without adding substantial molecular weight or hydrophobicity. Researchers may compare tetraglycine with longer glycine-serine linkers, PEG linkers, aminohexanoic acid spacers, or polysarcosine linkers to optimize delivery performance. In analytical chemistry, tetraglycine is useful as a model oligopeptide. Its simple composition makes it suitable for studying peptide fragmentation, chromatography, ionization, hydrolysis, and stability. It may be used in LC-MS method development, peptide standardization, degradation studies, and educational peptide chemistry workflows. Because it contains only glycine residues, interpretation of fragmentation patterns and degradation products is straightforward. Tetraglycine can also support structure-function studies of linker length. Researchers often test glycine linkers of different lengths, such as diglycine, triglycine, tetraglycine, pentaglycine, or glycine-serine repeats, to determine how spacing affects biological activity. In receptor-binding constructs, enzyme substrates, peptide inhibitors, and conjugates, small changes in linker length can substantially alter potency, cleavage rate, uptake, or binding affinity. Tetraglycine provides a defined midpoint in such linker comparison panels. Experimental controls should include linker-free constructs, shorter and longer oligoglycine analogs, glycine-serine linkers, unrelated peptide spacers, and payload-only or ligand-only controls. For conjugates, researchers should evaluate purity, identity, solubility, stability, target binding, and biological activity after linker incorporation. For enzymatic assays, enzyme-free, heat-inactivated enzyme, and time-course controls are recommended. Overall, tetraglycine is a simple but versatile oligopeptide for peptide science and biomolecular engineering. It supports flexible linker design, peptide synthesis, bioconjugation, chemical biology probe development, enzyme substrate construction, biomaterial functionalization, nanoparticle modification, analytical method development, and systematic optimization of spacing effects in complex molecular constructs.
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