Product Name: 2× ST-tag II TFA
Sequence: Trp-Ser-His-Pro-Gln-Phe-Glu-Lys-Trp-Ser-His-Pro-Gln-Phe-Glu-Lys
Purity: 95%
Storage : Sealed storage, away from moisture
Chemical Formula: C100H132N26O25.xC2HF3O2
Molar Mass: 2212.30 (free acid)
Application: 2× ST-tag II TFA is an oligopeptide tag designed for efficient, rapid, and specific linkage of proteins with double-stranded DNA molecules. As a peptide ligand of ST Tactin (STN), 2× ST-tag II TFA specifically binds to ST Tactin, enabling controlled protein capture, assembly, and conjugation workflows. This peptide is especially useful for constructing DNA–protein hybrids, where precise molecular recognition is required to connect biomolecules without nonspecific interactions. 2× ST-tag II TFA is widely used in chemical biology, protein engineering, molecular assembly, bioconjugation research, and development of DNA–protein hybrid systems for analytical and synthetic applications.
Current Research: Overview 2× ST-tag II TFA is an oligopeptide tag used for highly specific biomolecular linkage. It can link proteins and double-stranded DNA (dsDNA) molecules in an efficient, rapid, and specific manner. The active peptide motif, 2× ST-tag II, acts as a peptide ligand of ST-Tactin, also referred to as STN, and specifically binds to ST-Tactin. Because of this binding specificity, 2× ST-tag II TFA is useful for constructing DNA–protein hybrids and related biohybrid systems. Product references describe 2× ST-tag II TFA as an oligopeptide capable of connecting proteins and dsDNA molecules and as a reagent for DNA–protein hybrid construction. DNA–protein hybrids are important tools in chemical biology, molecular diagnostics, synthetic biology, biosensing, nanotechnology, and targeted delivery research. They combine the programmability of DNA with the structural, catalytic, binding, or recognition functions of proteins. However, the construction of these hybrids often requires conjugation strategies that are selective, reproducible, and compatible with folded proteins. 2× ST-tag II TFA is relevant to this field because it provides a peptide-based recognition element that can participate in site-specific assembly through ST-Tactin binding. Unlike nonspecific chemical crosslinking methods, affinity tag-based approaches allow more controlled molecular organization. The 2× ST-tag II/ST-Tactin interaction can be used to bring tagged peptides, proteins, or DNA-linked components together in a predictable manner. This makes 2× ST-tag II TFA a useful research reagent for designing DNA–protein conjugates, assembling hybrid nanostructures, and developing protein–nucleic acid interfaces. Structural and Functional Features of 2× ST-tag II TFA The name 2× ST-tag II indicates a duplicated ST-tag II peptide motif. ST-tag II is closely related to the Strep-tag II system, a short peptide affinity tag that binds engineered streptavidin variants known as Strep-Tactin or ST-Tactin. Strep-tag II is commonly described as an eight-amino-acid peptide sequence, WSHPQFEK, and can be placed at the N-terminus or C-terminus of recombinant proteins with limited interference in many protein systems. The duplicated 2× format can increase avidity compared with a single short tag by providing two peptide-binding elements. In affinity systems, multivalency can enhance binding strength, reduce dissociation, and improve stability of assembled complexes. This is particularly useful when constructing DNA–protein hybrids, where stable yet specific association between components is required. The TFA designation indicates the trifluoroacetate salt form. Peptides are commonly isolated as TFA salts after reverse-phase HPLC purification. The salt form can influence handling, solubility, and formulation, but the functional recognition activity is associated with the 2× ST-tag II peptide sequence itself. Specific Binding to ST-Tactin A central feature of 2× ST-tag II TFA is its specific binding to ST-Tactin/STN. ST-Tactin is an engineered streptavidin-based binding partner developed to recognize Strep-tag-type peptide motifs. The broader Strep-tag/Strep-Tactin technology is widely used for recombinant protein purification and detection because it enables specific, reversible, and relatively mild affinity interactions. Sources describing the Strep-tag system note that Strep-Tactin is an optimized streptavidin variant that binds Strep-tag peptides and can support gentle purification under physiological conditions. For DNA–protein hybrid construction, this interaction is valuable because it allows a peptide-tagged component to bind a defined ST-Tactin-containing partner. If one component is associated with dsDNA and another component is a protein of interest, ST-Tactin-mediated recognition can bring them together without requiring direct random chemical modification of the protein surface. This specificity is especially important for preserving protein function. Random crosslinking can modify lysines, cysteines, or other reactive residues near active sites or binding interfaces, leading to reduced activity or heterogeneous products. In contrast, affinity tag-based assembly can support more uniform orientation and reduce unwanted modification of functional protein regions. Construction of DNA–Protein Hybrids 2× ST-tag II TFA can be used to construct DNA–protein hybrids, a class of conjugates in which DNA and protein components are combined into a single functional system. Product descriptions specifically identify 2× ST-tag II as an oligopeptide that can link proteins and dsDNA molecules efficiently, rapidly, and specifically. DNA provides sequence programmability, predictable base-pairing, and compatibility with DNA nanotechnology. Proteins provide biological functions such as enzymatic catalysis, molecular recognition, signal generation, ligand binding, transport, or structural organization. By combining these two molecule types, researchers can create hybrid systems that are difficult to achieve with either DNA or proteins alone. Potential DNA–protein hybrid applications include biosensors, DNA nanostructure functionalization, protein arrays, enzyme positioning, molecular diagnostics, programmable biomaterials, and synthetic biology devices. In these systems, the ability to attach proteins to dsDNA in a defined manner is essential. 2× ST-tag II TFA supports this goal by providing a specific peptide ligand that can participate in ST-Tactin-mediated assembly. Advantages of Peptide Tag-Based DNA–Protein Linkage The use of 2× ST-tag II TFA offers several research advantages for DNA–protein hybrid construction. First, it supports specificity. The peptide tag binds ST-Tactin selectively, allowing targeted association between designed components. This reduces nonspecific background and improves reproducibility. Second, the method can be rapid. Affinity interactions generally occur under mild aqueous conditions without requiring lengthy chemical activation steps. This is useful when working with sensitive proteins, enzymes, antibodies, or DNA nanostructures. Third, the approach can be modular. Researchers can design one component to carry the 2× ST-tag II sequence and another component to present ST-Tactin. This modularity allows the same binding pair to be used across different proteins, DNA constructs, and assay platforms. Fourth, the method can help preserve protein activity. Because the protein does not necessarily require random chemical modification, the risk of damaging active sites or binding domains may be reduced. Fifth, the 2× tag format may improve binding stability through avidity effects, which can be useful for hybrid structures that must remain intact during washing, imaging, sensing, or assembly procedures. Relevance to Protein Engineering 2× ST-tag II TFA is also relevant to protein engineering because peptide tags are frequently used to control protein purification, immobilization, detection, and assembly. Strep-tag II and related systems are valued because the tag is small and often does not strongly interfere with protein folding or function. Reports on the broader Strep-tag system describe Strep-tag II as a short eight-amino-acid tag and emphasize its compatibility with many recombinant protein workflows. In DNA–protein hybrid work, engineered proteins may be designed with peptide tags that enable selective attachment to DNA scaffolds. This can help researchers position enzymes along DNA templates, organize multiple proteins in defined geometries, or create protein-decorated DNA nanostructures. The 2× ST-tag II/ST-Tactin pair provides one such assembly strategy. Protein engineering studies may also use this system to compare how tag position affects hybrid formation. A 2× ST-tag II motif may be placed at the N-terminus, C-terminus, or an engineered loop, depending on the protein structure and the desired orientation. The optimal placement should be determined experimentally, because protein accessibility, folding, and function can vary by construct. Applications in Current Research 2× ST-tag II TFA may be used in several research areas. In DNA–protein hybrid construction, it can help link proteins and dsDNA molecules through a specific ST-Tactin-binding interaction. In DNA nanotechnology, it may support the positioning of proteins on DNA origami, DNA scaffolds, or programmable nucleic acid assemblies. In biosensor development, DNA–protein hybrids can combine DNA-based recognition or amplification with protein-based signal generation, such as enzymes or binding proteins. In synthetic biology, 2× ST-tag II-mediated linkage may help assemble modular biomolecular systems containing genetic, enzymatic, or regulatory components. In protein immobilization, ST-Tactin binding can be used to anchor tagged proteins to surfaces, particles, or DNA-based materials. In bioconjugation research, 2× ST-tag II TFA provides an affinity-based alternative to random covalent crosslinking, supporting more controlled assembly of protein–nucleic acid structures. Research Considerations Researchers using 2× ST-tag II TFA should consider several experimental factors. First, the final assembly depends on the accessibility of the 2× ST-tag II motif. If the peptide is sterically blocked by a folded protein, DNA structure, or surface, ST-Tactin binding may be reduced. Second, the availability and presentation of ST-Tactin are critical. ST-Tactin should be positioned in a way that allows efficient interaction with the peptide tag without interfering with the dsDNA component or protein function. Third, binding conditions should be optimized. Buffer composition, salt concentration, pH, temperature, and competing ligands can influence affinity-based assembly. Because Strep-tag-type systems are related to streptavidin technology, biotin or desthiobiotin-like competitors may affect binding depending on the specific ST-Tactin format used. Fourth, the stability of the DNA–protein hybrid should be validated under the intended assay or application conditions. Washing, dilution, incubation time, nuclease exposure, and mechanical handling may affect complex retention. Fifth, analytical characterization is important. Researchers may use gel electrophoresis, EMSA, fluorescence assays, pull-down assays, surface plasmon resonance, biolayer interferometry, size-exclusion chromatography, mass spectrometry, atomic force microscopy, or electron microscopy to confirm hybrid formation, specificity, stoichiometry, and stability. Future Research Directions The ability to connect proteins and dsDNA in a rapid and specific manner is increasingly important as biomolecular engineering moves toward programmable hybrid systems. DNA nanotechnology can provide addressable architectures at nanometer scale, while proteins provide biological activity. 2× ST-tag II TFA supports this interface by enabling ST-Tactin-mediated linkage between peptide-tagged and DNA-associated components. Future research may explore improved DNA–protein hybrid platforms for diagnostics, spatially organized enzyme cascades, programmable biomaterials, and targeted delivery systems. Researchers may also compare 2× ST-tag II/ST-Tactin assembly with other conjugation methods, including biotin–streptavidin, SpyTag/SpyCatcher, HaloTag, SNAP-tag, click chemistry, and maleimide-thiol coupling. The value of 2× ST-tag II TFA lies in its modularity and specificity. As DNA–protein hybrid technologies become more sophisticated, peptide affinity tags such as 2× ST-tag II may help researchers build systems that are easier to assemble, more reproducible, and more compatible with sensitive biomolecules. Conclusion 2× ST-tag II TFA is an oligopeptide reagent used to link proteins and dsDNA molecules efficiently, rapidly, and specifically. The 2× ST-tag II peptide functions as a ligand of ST-Tactin/STN and specifically binds ST-Tactin, enabling its use in the construction of DNA–protein hybrids. In current research, 2× ST-tag II TFA is valuable for DNA–protein hybrid assembly, protein immobilization, DNA nanotechnology, biosensor development, and synthetic biology. By providing a specific peptide-based recognition element, it offers a controlled alternative to nonspecific crosslinking and supports the development of programmable biomolecular systems that combine the strengths of proteins and dsDNA.
Get a Quote
