When workin 3X FLAG peptide ; Molecular Weight, 2861.87 ; Formula, C120H169N31O49S ; Cas No. 402750-12-3 ; Smiles g with affinity-based purification techniques, understanding the precise flag peptide molecular weight is essential for researchers aiming to optimize elution efficiency. In my experience with laboratory workflows, distinguishing between standard constructs and multi-repeat versions is critical for calculating accurate molar ratios during experimental procedures.
The Standard FLAG Peptide: DYKDDDDK
The classic FLAG peptide consists of the eight-amino-acid sequence DYKDDDDK. It is widely recognized for its hydrophilic nature and high charge density. Through my review of technical data, the established molecular weight: 1012.97 daltons (often rounded to 1013.0 g/mol) is the standard benchmark.
For those looking at chemical properties, the formula is generally cited as $C_{41}H_{60}N_{10}O_{20}$, with a CAS number of 98849-88-8. In practice, I have found that when dealing with lyophilized powder, ensuring proper reconstitu FLAG Tag Protein Purification tion—often targeting a concentration near 98.72 mM or similar working stocks—is vital for maintaining structural integr Molecular Formula, C41H60N10O ; Molecular Weight, 1012.97 ; Purity, > 95% ; Solubility, Soluble in Ultrapure water under 1mg/ml ; Form, Lyophilized. ity. Whether you refer to it as 1012.97 or simply 1012 Da, t Molecular Formula, C41H60N10O ; Molecular Weight, 1012.97 ; Purity, > 95% ; Solubility, Soluble in Ultrapure water under 1mg/ml ; Form, Lyophilized. his tag remains by C Set-Up — The 3X FLAG® Peptide is a synthetic peptide of. 23 amino acid residues, with a calculated molecular weight of 2,864 Da, where the. the gold standard for specific tag-based separation.
The Evolution to 3X FLAG Peptide
As research requirements have grown more sophisticated, the 3X FLAG peptide has become a frequent necessity. This synthetic version, composed of 23 amino acid residues, offers significantly higher affinity for elution.
The molecular weight, 2861.87 (sometimes noted as molecular weight 2864 depending on the specific salt form or hydration state), represents a substantial increase over the single construct. Its formula, $C_{120}H_{169}N_{31}O_{49}S$, reflects the complex nature of this multi-repeat sequence. In my own protocols, I treat this as having a calculated molecular weight of 2,864 Da, which is a helpful figure to keep in mind when calculating the necessary mass for a specific elution buffer volume.
Comparison of Molecular Metrics
When analyzing your data, it is helpful to keep a clear table of these values:
| Peptide Type | Typical Molecular Weight | Notes |
|---|---|---|
| FLAG Peptide | 1012.97 | Standard 8-amino acid sequence |
| 3X FLAG Peptide | 2861.87 | 23-amino acid synthetic construct |
Some technical documents might note a molecular weight (MW): 2730.71 Da for specific modified versions, so always verify the datasheet provided with your specific lot. Whether you are calculating molar mass for stoichiometric binding or simply preparing buffer, note that the MW (average): 1012.99 is consistent across most high-purity Why do flag tagged proteins have higher molecular weight synthetic batches.
Practical Considerations for Handling
From personal observation, these peptides are highly sensitive to storage conditions. To maintain the integrity of the 1012.96 Da or 2,861.87 Da constructs, always store them at -20°C in a desiccated environment.
If you are investigating why a tagged protein appears at a higher position on a gel, remember that the flag peptide itself contributes roughly 1 kDa to the total mass. This is a minor shift, but when using the 3X variant, the shift is more pronounced. Always conside FLAG: The Epitope Tag Peptide r the molecular weight of your construct plus the tag to account for the total migration rate accurately.
By maintaining a clear understanding of these values—from the M.Wt, 1012.97 of the monomer to the M.Wt, 2861.87 of the trimer—you can ensure your elution protocols remain consistent and reproducible. Always consult the specific certificate of analysis provided by your supplier to confirm the purity and exact mass for your specific experiment.