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| Targets |
The X-press Tag Peptide itself is a peptide sequence, not a drug; therefore, it does not have a pharmacological target. Its molecular "target" is the specific binding site on the Anti-Xpress antibody (e.g., a monoclonal antibody raised against the Xpress epitope). The polyhistidine sequence targets nickel- or cobalt-charged nitrilotriacetic acid (NTA) resin used in immobilized metal affinity chromatography (IMAC). The enterokinase cleavage site is a substrate for the protease enterokinase, which recognizes and specifically cleaves after the lysine residue in the DDDDK sequence. This tag is used as a molecular tool to capture and purify proteins of interest, enabling the study of protein function, interactions, and structure without directly targeting a biological pathway.
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| ln Vitro |
The X-press Tag Peptide is not a drug and thus does not possess pharmacologic "activity" in the traditional sense. Its activity is defined by its ability to bind to Anti-Xpress antibodies and to metal affinity resins. Binding to Anti-Xpress antibody is highly specific, allowing for detection and purification of Xpress-tagged fusion proteins in Western blotting, ELISA, immunoprecipitation (IP), and immunofluorescence (IF) applications. The polyhistidine region provides high affinity for nickel and cobalt ions, enabling efficient one-step purification of tagged proteins under native or denaturing conditions. The peptide is considered highly effective for its intended use, with minimal nonspecific binding. It is supplied in high purity (typically >95%) and is used to generate standard controls for protein expression experiments.
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| ln Vivo |
As a research tool, the X-press Tag Peptide is not tested in animal models for efficacy. Its "in vivo activity" is not relevant because it is not administered to animals as a therapeutic. However, the tag is used to study the expression of recombinant proteins that are delivered in vivo. For example, a viral vector encoding an Xpress-tagged protein can be injected into mice, and the expression of that protein in specific tissues can then be detected using Anti-Xpress antibody. The tag itself is inert and does not affect the biological activity or distribution of the target protein to a significant extent. The peptide is also used as a blocking reagent in ELISA and other immunoassays to reduce nonspecific background when using Anti-Xpress antibodies.
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| Enzyme Assay |
As a peptide sequence, the X-press Tag Peptide is not used in traditional enzyme/receptor binding assays. Its interaction with antibodies is assessed using standard immunoassay protocols. For ELISA, the peptide is directly coated onto a 96-well plate, or conjugated to a carrier protein such as BSA (bovine serum albumin). After blocking, the plate is incubated with an Anti-Xpress antibody (primary antibody) at varying concentrations for 1-2 hours at room temperature. After washing, a secondary HRP-conjugated antibody is added, and the signal is developed with a substrate like TMB (3,3',5,5'-Tetramethylbenzidine). The absorbance is read at 450 nm to generate a binding curve. Surface plasmon resonance (SPR) can be used to measure the binding affinity (KD) of the peptide for the Anti-Xpress antibody. Purity and sequence are confirmed by HPLC and mass spectrometry (MS).
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| Cell Assay |
X-press Tag Peptide is not added to live cells; instead, it is used to detect tagged proteins expressed in cells. The typical cellular workflow involves transfecting or transducing cells with a plasmid or viral construct encoding a fusion protein that includes the X-press tag. After 24-72 hours, the cells are lysed, and the Xpress-tagged protein is purified from the cell lysate using metal affinity resin (e.g., Ni-NTA agarose). The presence and purity of the purified protein are then analyzed by SDS-PAGE and Western blotting using an Anti-Xpress antibody. Alternatively, cells are fixed, permeabilized, and incubated with Anti-Xpress antibody, followed by a fluorescently labeled secondary antibody, to visualize the subcellular localization of the tagged protein by fluorescence microscopy. The peptide itself is used as a blocking or competitive reagent in these assays.
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| Animal Protocol |
No in vivo animal experiments are performed with the X-press Tag Peptide as an administered substance. The peptide is used to study protein expression and localization in animals. A typical protocol for a mouse study would involve injecting a recombinant adeno-associated virus (AAV) or a lentivirus encoding the Xpress-tagged protein of interest via tail vein injection or intratracheal administration. After 2-4 weeks, the mice are euthanized, and tissues (e.g., lung, liver, brain) are collected. The tissues are homogenized, and the protein lysates are then subjected to Xpress-tag purification using Ni-NTA agarose or to SDS-PAGE followed by Western blotting with Anti-Xpress antibody to confirm expression of the recombinant protein. For localization, tissue sections are subjected to immunohistochemistry (IHC) using Anti-Xpress antibody as the primary reagent. The peptide can be used as a blocking agent to validate antibody specificity in these assays.
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| ADME/Pharmacokinetics |
The X-press Tag Peptide is a synthetic peptide, and its pharmacokinetic properties are not studied for drug development. As a peptide, if administered systemically, it would be rapidly degraded by proteases in the blood and tissues. It has a short plasma half-life, likely on the order of minutes. The peptide is hydrophilic due to its multiple aspartic acid residues and is soluble in aqueous buffers, such as PBS (phosphate-buffered saline) at neutral pH. It is not membrane-permeable due to its small size and lack of lipophilicity. For long-term storage, the lyophilized powder should be stored at -20degC and protected from moisture. Solutions should be aliquoted and stored at -80degC for up to six months to avoid repeated freeze-thaw cycles, which can degrade the peptide.
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| Toxicity/Toxicokinetics |
The X-press Tag Peptide has not been extensively studied for toxicity, as it is not a drug intended for human consumption. As a short peptide composed of natural amino acids, it is generally considered to have very low toxicity. In standard laboratory use, it is considered a low-hazard chemical. However, as with all synthetic peptides, precautions should be taken to avoid inhalation, ingestion, and skin contact, as it may be a mild irritant. The peptide is not considered genotoxic or cytotoxic at the concentrations used in typical experiments (ng to microg/mL). It is for research use only and is not intended for any clinical, diagnostic, or therapeutic applications. Disposal should be performed in accordance with local regulations for non-hazardous biological waste.
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| Additional Infomation |
X-press Tag Peptide (sequence: DLYDDDDK) is a widely used affinity tag in molecular biology. It is commercially available as a synthetic peptide and is often used as a standard or control in experiments employing Anti-Xpress antibody. The Xpress epitope is a trademarked term of Invitrogen (now Thermo Fisher Scientific), and the tag is included in their proprietary expression vectors, such as the pTrcHis, pBAD/His, and pRSET series. The tag provides a dual advantage: the polyhistidine portion allows for rapid purification, while the Xpress epitope permits sensitive detection. The enterokinase cleavage site enables the removal of the tag from the target protein, if desired, to study the native protein. This product is an essential tool for researchers who require a robust system for expressing and purifying recombinant proteins. It is supplied for research purposes only and is not approved for therapeutic or diagnostic use in humans.
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| Molecular Formula |
C41H59N9O20
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| Molecular Weight |
997.96
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| Exact Mass |
997.388
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| CAS # |
339988-16-8
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| PubChem CID |
10290593
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| Appearance |
White to off-white solid powder
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| Density |
1.455±0.06 g/cm3(Predicted)
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| Boiling Point |
1548.9±65.0 °C(Predicted)
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| LogP |
0
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| Hydrogen Bond Donor Count |
16
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| Hydrogen Bond Acceptor Count |
22
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| Rotatable Bond Count |
33
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| Heavy Atom Count |
70
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| Complexity |
1910
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| Defined Atom Stereocenter Count |
8
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| SMILES |
CC(C)C[C@@H](C(=O)N[C@@H](CC1=CC=C(C=C1)O)C(=O)N[C@@H](CC(=O)O)C(=O)N[C@@H](CC(=O)O)C(=O)N[C@@H](CC(=O)O)C(=O)N[C@@H](CC(=O)O)C(=O)N[C@@H](CCCCN)C(=O)O)NC(=O)[C@H](CC(=O)O)N
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| InChi Key |
FWMNKRVHBHKBMO-VXBMVYAYSA-N
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| InChi Code |
InChI=1S/C41H59N9O20/c1-18(2)11-23(45-34(62)21(43)13-29(52)53)35(63)46-24(12-19-6-8-20(51)9-7-19)36(64)47-26(15-31(56)57)38(66)49-28(17-33(60)61)40(68)50-27(16-32(58)59)39(67)48-25(14-30(54)55)37(65)44-22(41(69)70)5-3-4-10-42/h6-9,18,21-28,51H,3-5,10-17,42-43H2,1-2H3,(H,44,65)(H,45,62)(H,46,63)(H,47,64)(H,48,67)(H,49,66)(H,50,68)(H,52,53)(H,54,55)(H,56,57)(H,58,59)(H,60,61)(H,69,70)/t21-,22-,23-,24-,25-,26-,27-,28-/m0/s1
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| Chemical Name |
(2S)-6-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-amino-3-carboxypropanoyl]amino]-4-methylpentanoyl]amino]-3-(4-hydroxyphenyl)propanoyl]amino]-3-carboxypropanoyl]amino]-3-carboxypropanoyl]amino]-3-carboxypropanoyl]amino]-3-carboxypropanoyl]amino]hexanoic acid
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| HS Tariff Code |
2934.99.9001
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| Storage |
Powder -20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month Note: Please store this product in a sealed and protected environment (e.g. under nitrogen), avoid exposure to moisture and light. |
| Shipping Condition |
Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)
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| Solubility (In Vitro) |
H2O: ≥ 100 mg/mL (100.20 mM)
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| Solubility (In Vivo) |
Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.
Injection Formulations
Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)(e.g. IP/IV/IM/SC) *Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution. Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline) Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil) Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals). View More
Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)] Oral Formulations
Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium) Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals). View More
Oral Formulation 3: Dissolved in PEG400 (Please use freshly prepared in vivo formulations for optimal results.) |
| Preparing Stock Solutions | 1 mg | 5 mg | 10 mg | |
| 1 mM | 1.0020 mL | 5.0102 mL | 10.0204 mL | |
| 5 mM | 0.2004 mL | 1.0020 mL | 2.0041 mL | |
| 10 mM | 0.1002 mL | 0.5010 mL | 1.0020 mL |
*Note: Please select an appropriate solvent for the preparation of stock solution based on your experiment needs. For most products, DMSO can be used for preparing stock solutions (e.g. 5 mM, 10 mM, or 20 mM concentration); some products with high aqueous solubility may be dissolved in water directly. Solubility information is available at the above Solubility Data section. Once the stock solution is prepared, aliquot it to routine usage volumes and store at -20°C or -80°C. Avoid repeated freeze and thaw cycles.
Calculation results
Working concentration： mg/mL；
Method for preparing DMSO stock solution： mg drug pre-dissolved in μL DMSO (stock solution concentration mg/mL). Please contact us first if the concentration exceeds the DMSO solubility of the batch of drug.
Method for preparing in vivo formulation:：Take μL DMSO stock solution, next add μL PEG300, mix and clarify, next addμL Tween 80, mix and clarify, next add μL ddH2O，mix and clarify.
(1) Please be sure that the solution is clear before the addition of next solvent. Dissolution methods like vortex, ultrasound or warming and heat may be used to aid dissolving.
(2) Be sure to add the solvent(s) in order.
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