PAR1
Protease-activated receptor 1 (PAR-1). Functions as a PAR-1-specific antagonist peptide, competitively binding to the receptor and blocking its activation by agonists like thrombin or TRAP-6 without triggering receptor signaling.

Recent studies on cloning of the thrombin receptor, which belongs to the family of G-protein-coupled receptors, suggest that thrombin cleaves a peptide from the extracellular N-terminus. A synthetic peptide of 14 amino acids corresponding to the sequence of the newly generated N-terminus was found to possess thrombin-like activity in several cells endowed with thrombin receptors. The relaxant and contractile effects of this thrombin receptor activating peptide (TRAP, Ser-Phe-Leu-Leu-Arg-Asn-Pro-Asn-Asp-Lys-Tyr-Glu-Pro-Phe) were investigated in porcine pulmonary arteries and compared with the action of thrombin. In PGF2 alpha-precontracted vessels with intact endothelium, TRAP (0.3-10 mumol/l) caused reversible transient and concentration-dependent relaxation which was absent after mechanical removal of the endothelium. Preincubation of the vessels with NG-nitro-L-arginine (200 mumol/l) markedly reduced the relaxation. The TRAP-induced relaxation was associated with an increase in cGMP in the arteries. In comparison to thrombin, TRAP (EC50: 0.8 mumol/l) was less potent by more than three orders of magnitude. In endothelium-denuded pulmonary arteries TRAP (1-20 mumol/l) caused a concentration-dependent contraction which was reversible after washout. The TRAP-induced contractile response was preceded by an increase in generation of inositol 1,4,5-triphosphate (IP3); the peak of IP3 accumulation was reached after 30 s. Compared with the contractile effect of thrombin, that of TRAP was weaker by three of magnitude. The vascular effect of TRAP was not inhibited by the thrombin inhibitors hirudin or heparin while the protein kinase C inhibitor staurosporine (0.1 mumol/l) preferentially inhibited the tonic phase of contraction [1].

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TRAP-6 (2-6) inhibits platelet aggregation induced by the PAR-1 agonist SFLLRN or by thrombin in vitro. It is used to study the minimal sequence required for PAR-1 antagonism and to map the receptor's ligand-binding site. The peptide may inhibit PAR-1-mediated signaling in other cell types, including endothelial cells and smooth muscle cells, blocking calcium mobilization and downstream signaling pathways. Specific IC50 values for antagonism are not extensively reported.

In vivo, TRAP-6 (2-6) can be used to antagonize PAR-1 in animal models, although specific studies are limited. Its effects would be opposite to those of PAR-1 agonists, potentially inhibiting platelet aggregation and thrombosis. It may be used to study the role of PAR-1 in inflammation, vascular function, and pain modulation by blocking receptor activation.

PAR-1 receptor binding assay: Membranes from cells expressing PAR-1 are incubated with a radiolabeled PAR-1 agonist (e.g., [3H]TRAP-6 or [¹2⁵I]SFLLRN) and varying concentrations of TRAP-6 (2-6) (0.01-10,000 nM) in binding buffer for 1-2 hours at room temperature. Bound radioactivity is separated by filtration and quantified. Competition for binding indicates receptor antagonism.

Platelet aggregation assay: Platelet-rich plasma (PRP) is pre-incubated with TRAP-6 (2-6) (1-1000 uM) for 5-10 minutes at 37degC, then stimulated with an agonist like thrombin (0.1-1 U/mL) or TRAP-6 (10-100 uM). Aggregation is monitored using a platelet aggregometer (increase in light transmission). Inhibition of aggregation is calculated relative to agonist-only controls. IC50 for antagonism is determined from dose-response curves. Calcium mobilization assay: Cells expressing PAR-1 are loaded with Fluo-4 AM, pre-incubated with TRAP-6 (2-6), then stimulated with TRAP-6 or thrombin. Inhibition of calcium flux is measured using a fluorescence plate reader.

Animal models of thrombosis: TRAP-6 (2-6) could be administered to assess its ability to inhibit platelet aggregation and thrombus formation in vivo, though specific studies are not detailed. Typically, the peptide would be administered intravenously prior to induction of thrombosis (e.g., by ferric chloride or laser injury), and thrombus formation would be monitored by intravital microscopy or Doppler flowmetry.

As a peptide (MW 661.79), it is expected to have a short half-life and rapid clearance in vivo. Not orally bioavailable; requires parenteral administration (intravenous or intraperitoneal).

No specific toxicity data are reported. As a research peptide, it is not intended for therapeutic use.

[1]. Relaxant and contractile responses of porcine pulmonary arteries to a thrombin receptor activating peptide (TRAP). Naunyn Schmiedebergs Arch Pharmacol. 1994 Apr;349(4):431-6.

This is a research peptide, not an approved drug. It serves as a tool to study PAR-1 antagonism and the structural requirements for receptor activation. Also known as FLLRN. It is a biologically active peptide serving as a PAR-1-specific antagonist peptide.

C31H51N9O7

661.79274

661.391

141136-84-7

44149309

White to off-white solid powder

1.35g/cm3

1.615

2.966

9

9

21

47

1090

5

CC(C)C[C@@H](C(=O)N[C@@H](CC(C)C)C(=O)N[C@@H](CCCN=C(N)N)C(=O)N[C@@H](CC(=O)N)C(=O)O)NC(=O)[C@H](CC1=CC=CC=C1)N

WBNIBLBGDVPFOO-LSBAASHUSA-N

InChI=1S/C31H51N9O7/c1-17(2)13-22(38-26(42)20(32)15-19-9-6-5-7-10-19)29(45)39-23(14-18(3)4)28(44)37-21(11-8-12-36-31(34)35)27(43)40-24(30(46)47)16-25(33)41/h5-7,9-10,17-18,20-24H,8,11-16,32H2,1-4H3,(H2,33,41)(H,37,44)(H,38,42)(H,39,45)(H,40,43)(H,46,47)(H4,34,35,36)/t20-,21-,22-,23-,24-/m0/s1

(2S)-4-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-amino-3-phenylpropanoyl]amino]-4-methylpentanoyl]amino]-4-methylpentanoyl]amino]-5-(diaminomethylideneamino)pentanoyl]amino]-4-oxobutanoic acid

FLLRN; 141136-84-7; Phe-leu-leu-arg-asn; Phenylalanyl-leucyl-leucyl-arginyl-asparagine; H 8325; H-8325; (2S)-4-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-amino-3-phenylpropanoyl]amino]-4-methylpentanoyl]amino]-4-methylpentanoyl]amino]-5-(diaminomethylideneamino)pentanoyl]amino]-4-oxobutanoic acid; L-Asparagine, N2-(N2-(N-(N-L-phenylalanyl-L-leucyl)-L-leucyl)-L-arginyl)-;

2934.99.9001

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.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ~100 mg/mL (~151.11 mM)

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.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*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).

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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)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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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).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)