Enfuvirtide (T-20) is a 36-amino-acid synthetic peptide derived from the HR2 region of HIV-1 gp41. The peptide is N-terminally acetylated and C-terminally amidated and was developed as the first approved member of the HIV fusion-inhibitor class.
Mechanistically, Enfuvirtide binds the HR1 region of gp41, preventing HR1–HR2 association and formation of the six-helix bundle required to bring the viral and host-cell membranes together. This makes T-20 a well-defined research tool for HIV-1 entry, gp41-mediated membrane fusion, fusion-inhibitor resistance and peptide–protein interaction studies.
Product Information
| Product Name | Enfuvirtide (T-20) |
| Catalog No. | AS2507 |
| CAS No. | 159519-65-0 |
| Sequence | Ac-Tyr-Thr-Ser-Leu-Ile-His-Ser-Leu-Ile-Glu-Glu-Ser-Gln-Asn-Gln-Gln-Glu-Lys-Asn-Glu-Gln-Glu-Leu-Leu-Glu-Leu-Asp-Lys-Trp-Ala-Ser-Leu-Trp-Asn-Trp-Phe-NH2 |
| Peptide Length | 36 residues |
| Molecular Formula | C204H301N51O64 |
| Molecular Weight | Approximately 4492.0 Da |
| N-Terminus | Acetylated |
| C-Terminus | Amidated |
| Primary Target | HIV-1 gp41 HR1 region |
| Mechanism | Viral membrane fusion inhibitor |
HR2-Derived Peptide That Binds gp41 HR1
A key mechanistic distinction is that Enfuvirtide is derived from the gp41 HR2 region but binds to HR1. During HIV-1 entry, HR1 and HR2 normally associate to form a six-helix bundle that drives viral and cellular membranes into close proximity.
Enfuvirtide competitively associates with exposed HR1 during the gp41 conformational transition. This prevents productive HR1–HR2 packing and arrests membrane fusion before viral entry is completed.
Why the HR1/HR2 Distinction Matters
Describing T-20 as binding HR2 reverses the actual molecular interaction and can lead to incorrect interpretation of fusion-inhibitor experiments. HR2 is the structural origin of the T-20 sequence; HR1 is its principal gp41 binding region.
We recommend preserving this distinction when comparing Enfuvirtide with other gp41-derived fusion inhibitors, resistance mutations or engineered HR2 peptides.
Research Applications
Enfuvirtide can support HIV-1 entry studies, gp41 membrane-fusion research, HR1–HR2 interaction assays, fusion-inhibitor resistance studies and development of peptide-based antiviral entry inhibitors.
Custom antiviral peptides, terminal modifications and sequence variants are available through our Chemical Peptide Synthesis service.
Frequently Asked Questions
Does Enfuvirtide bind gp41 HR1 or HR2?
It binds HR1. Enfuvirtide itself is derived from an HR2-region sequence of HIV-1 gp41.
How does T-20 inhibit HIV-1 entry?
It prevents HR1 and HR2 from assembling into the six-helix bundle required for viral and cellular membrane fusion.
How many amino acids are in Enfuvirtide?
Enfuvirtide contains 36 amino acid residues.
What are the terminal modifications?
The N-terminus is acetylated and the C-terminus is amidated.