Pan-Coronavirus Fusion Inhibitor

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Pan-coronavirus fusion inhibitor - InvitroFit™

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25 µg

100 µg

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Lipopeptide-based SARS-CoV-2 fusion inhibitor

EK1C4 is a lipopeptide that potently inhibits SARS-CoV-2 (and other human coronaviruses, HCoV) fusion with target cells [1]. It is derived from the EK1 peptide to which cholesterol has been covalently attached in the C-terminal, with the help of a flexible polyethylene glycol (PEG) spacer [1]. 


Mode of action:

Inhibition of Spike-mediated cell fusion by EK1C4
Inhibition of Spike-mediated cell fusion by EK1C4

EK1C4 binds to a region of the virus Spike (S) protein that is crucial for fusion with the target cell. EK1C4, like EK1, interacts with the heptad repeat domain 1 (HR1) in the S2 subunit of the Spike protein [1,2]. These inhibitors prevent the HR1 and HR2 trimer association to form a six-helix bundle (6-HB) which brings the viral and target cell membranes in close proximity for fusion. EK1C4 has been described as the most potent HCoV fusion/entry inhibitor among EK1 and EK1-derived molecules in cellular assays using pseudotyped or live coronaviruses [1]. It has been suggested that the cholesterol group improves the anti-viral activity of EK1C4, possibly through anchoring the inhibitor to the target membrane, or binding to the hydrophobic groove on HR1 trimers [1]. Intranasally applied EK1C4 protects mice against HCoV-OC43 infection  [1]. This lipopeptide has thus the potential to be developed as a pan-coronavirus prophylactic or therapeutic, alone or in combination with neutralizing anti-Spike antibodies.

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Available upon requestAvailable upon request:

Bulk quantities available upon request: contact us

Key features:

  • Potent inhibitor of HCoV fusion/infection of target cells 
  • InvitroFit™ grade: highly pure (≥95%) and inhibitory function validated in cellular assays


Learn moreLearn more about InvivoGen's cell fusion assays


EK1C4 provided by InvivoGen is for research use only.



1. Xia, S et al., 2020. Inhibition of SARS-CoV-2 (previously 2019-nCoV) infection by a highly potent pan-coronavirus fusion inhibitor targeting its spike protein that harbors a high capacity to mediate membrane fusion. Cell Research. 30(4):343-355.
2. Xia, S et al., 2020. Fusion mechanism of 2019-nCoV and fusion inhibitors targeting HR1 domain in spike protein. Cell Mol. Immunol. 17:765-767.


Dose-dependent inhibition of cell-cell fusion
Dose-dependent inhibition of cell-cell fusion

EK1C4 is a potent inhibitor of SARS-CoV-2 Spike-mediated fusion between cells.
293-hMyD88 cells were transfected with expression plasmids encoding either the Wuhan (original) or Delta (B.1.617.2) Spike variant. 293-hMyD88-Spike “donor” cells were co-cultured with HEK-Blue™ hACE2 “acceptor” cells in the presence of increasing concentrations of EK1C4 or EK1. After overnight incubation, the neutralizing ability of EK1C4 and EK1 was determined by measuring the reduction of SEAP production in the supernatant using the QUANTI‑Blue™ Solution detection reagent. Data are shown as a percentage (%) of maximal inhibition of cell-cell fusion.

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Synonym: (N)EK1-GSGSG-PEG4-(Chol)

CAS number: 2428532-99-2

Formula: C250H405N51O78S2

Molecular weight: 5433.9 g/mol

Solubility: 5 mg/ml in DMSO

Quality control:

  • Purity ≥95% (UHPLC)
  • Inhibitory activity validated in cellular assays
  • The absence of bacterial contamination (e.g. lipoproteins and endotoxins) is confirmed using HEK-Blue™ TLR2 and HEK-Blue™ TLR4 cells.
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EK1C4 is provided as a dried powder and is available in two pack sizes:

  • 25 μg: inh-ek1c4
  • 100 μg (4 x 25 μg): inh-ek1c4-1

room temperature EK1C4 is shipped at room temperature.

store Upon receipt, store at -20 °C.

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Inhibition of Spike-mediated cell fusion with EK1C4:

ek1c4 mode of action

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