Influenza Hemagglutinin (HA) Peptide: High-Purity Tag for Protein Detection & Purification

Executive Summary: The Influenza Hemagglutinin (HA) Peptide is a nine-amino acid synthetic epitope tag (sequence: YPYDVPDYA) derived from the influenza virus HA protein, widely deployed for the detection, purification, and elution of HA-tagged fusion proteins in molecular biology (A6004 product page). The peptide exhibits exceptional solubility (≥55.1 mg/mL in DMSO, ≥100.4 mg/mL in ethanol, ≥46.2 mg/mL in water) and is supplied at >98% purity, confirmed by HPLC and MS, supporting reliable research results (internal benchmark). The HA tag specifically enables competitive displacement from anti-HA antibodies, streamlining immunoprecipitation and protein-protein interaction studies (Dong et al., 2025). Long-term stability is maintained by storage at -20°C in a desiccated state. The HA tag is integral in workflows analyzing posttranslational modifications, such as ubiquitination, and in dissecting protein signaling complexes (see mechanistic review).

Biological Rationale

The Influenza Hemagglutinin (HA) Peptide was engineered as a minimal, linear epitope tag derived from the influenza A hemagglutinin surface glycoprotein. Its conserved sequence, YPYDVPDYA, is recognized with high affinity by well-characterized monoclonal anti-HA antibodies (A6004 kit). This design allows the HA tag to function as an exogenous, non-disruptive marker for recombinant proteins in mammalian, insect, and yeast systems (see application guide). The HA tag’s small size (9 amino acids, ~1 kDa) minimizes steric hindrance and preserves protein function. It does not occur naturally in most model organisms, which reduces background and cross-reactivity (internal review).

Mechanism of Action of Influenza Hemagglutinin (HA) Peptide

The HA epitope tag operates by providing a unique, high-affinity binding site for monoclonal or polyclonal anti-HA antibodies. In immunoprecipitation assays, HA-tagged fusion proteins bind to anti-HA antibody-conjugated beads. The addition of free Influenza Hemagglutinin (HA) Peptide competitively displaces the tagged protein from the antibody, enabling controlled elution (product documentation). This competitive binding is sequence-specific and reversible under physiologic buffer conditions (pH 7.2–7.6, 4–25°C). The HA tag can be genetically fused to N- or C-termini of target proteins without loss of antibody recognition (see co-IP benchmarking). The tag's utility extends to Western blot, immunofluorescence, and flow cytometry, leveraging the same antigen-antibody specificity.

Evidence & Benchmarks

• HA peptide enables competitive elution of HA-tagged proteins from anti-HA affinity resins, with >95% recovery in standard immunoprecipitation workflows (A6004, product page).
• Supplied peptide purity exceeds 98%, confirmed by both HPLC and mass spectrometry under manufacturer QC protocols (A6004 documentation).
• Solubility benchmarks: ≥55.1 mg/mL in DMSO, ≥100.4 mg/mL in ethanol, ≥46.2 mg/mL in water. These values support use in a diverse range of buffers (A6004 tech sheet).
• HA tag is validated as a robust tool in studies of protein-protein interactions and posttranslational modifications, including ubiquitination/AKT-mTOR pathway mapping (Dong et al., DOI:10.1002/advs.202504704).
• Use of HA peptide in competitive elution is cited in translational research for dissecting E3 ligase-substrate relationships, such as NEDD4L-PRMT5 interactions in cancer models (Dong et al., 2025).

Applications, Limits & Misconceptions

The Influenza Hemagglutinin (HA) Peptide is routinely used for:

• Immunoprecipitation (IP) and co-immunoprecipitation (co-IP) of HA-tagged proteins.
• Competitive elution of HA-tagged fusion proteins from anti-HA magnetic or agarose beads.
• Protein-protein interaction mapping, especially in studies involving posttranslational modification analysis (Dong et al., 2025).
• Protein detection via Western blot, immunofluorescence, and flow cytometry with anti-HA antibodies.
• Quantitative proteomics when precise elution from anti-HA affinity supports is required.

Common Pitfalls or Misconceptions

• The HA peptide does not enable elution of non-HA-tagged proteins; it is specific for the YPYDVPDYA epitope.
• HA peptide is not a substitute for antibody-based detection in Western blot or ELISA; it is used for competitive elution and as a standard.
• Peptide solutions are not recommended for long-term storage; use lyophilized powder stored at -20°C, desiccated, for optimal stability.
• The tag does not interfere with protein function in most cases but may have subtle effects if fused within functionally critical regions.
• Cross-reactivity is minimal, but rare nonspecific binding can occur in highly complex lysates; always confirm with appropriate controls.

This article extends the mechanistic focus of "From Mechanism to Mission: Influenza Hemagglutinin (HA) Peptide" by providing granular, benchmarked data relevant to co-IP and elution conditions. It also updates the application scope presented in "Revolutionizing Protein Complex Analysis" with new insights from recent signal transduction research.

Workflow Integration & Parameters

For optimal immunoprecipitation, add the Influenza Hemagglutinin (HA) Peptide at 0.5–2 mg/mL in elution buffer (e.g., Tris-buffered saline, pH 7.5) to anti-HA resin after washing. Incubate at 4°C for 15–30 min with gentle agitation. The peptide’s high solubility allows preparation of concentrated stocks (up to 100.4 mg/mL in ethanol). Avoid repeated freeze-thaw cycles of dissolved peptide; aliquot as needed. Confirm elution efficiency by SDS-PAGE and Western blot using anti-HA antibodies. For stability, store lyophilized peptide at -20°C, protected from moisture; do not store dissolved peptide for more than 1 week at 4°C (A6004 kit guidance).

Conclusion & Outlook

The Influenza Hemagglutinin (HA) Peptide (A6004) is a high-purity, versatile tag for protein detection, purification, and elution in molecular biology. Its sequence specificity, robust solubility, and low cross-reactivity make it integral to advanced protein-protein interaction and ubiquitination studies (Dong et al., 2025). As molecular biology evolves towards more complex interactome and posttranslational modification mapping, the HA tag will remain a cornerstone for reproducible, scalable workflows. For detailed mechanistic optimization, consult our precision tag application guide, which this article further contextualizes with benchmark data and updated workflow integration.