B7-33
Single-chain relaxin analog · RXFP1 agonist
Overview
B7-33 is a 26-amino-acid single-chain peptide analog of native relaxin-2 (H2-relaxin), engineered to retain the RXFP1 receptor agonism of the parent two-chain relaxin while being synthesizable as a simple single-chain peptide rather than the disulfide-bonded heterodimer of native relaxin. The molecule is a biased RXFP1 agonist, preferentially activating the ERK1/2 pathway downstream of RXFP1 while showing reduced activation of the cAMP pathway, a pharmacological profile that the developing group hypothesized would produce the anti-fibrotic and tissue-remodeling effects of relaxin without the dose-limiting cardiovascular effects associated with full-agonism dosing. Lyochem supplies B7-33 as a lyophilized 26-residue peptide at ≥99.0% HPLC purity. As a single-chain linear peptide (no disulfide bridges), B7-33 is significantly easier to synthesize than the native disulfide-bonded relaxin heterodimer, this is the practical advantage of the biased-agonist design beyond the pharmacology. The analytical packet covers peak-integration HPLC, mass spec, and sequence verification on request. Two fill sizes (2 mg and 10 mg) cover typical research workflows in fibrosis, cardiovascular, and tissue-remodeling research models.
Who buys this, and why
Repair peptides — BPC-157, TB-500, B7-33, PEG-MGF — ship primarily to research labs studying tissue-repair, gastrointestinal-mucosa, tendon-ligament, and vascular-endothelial models. The synthesis itself is reliable, but analytical confirmation is where suppliers differ: buyers qualifying a new source should request sequence verification by tandem MS on the first lot and compare against the labelled sequence directly.
Primary buyer fit: academic and contract research laboratories.
Specifications
- CAS
- 1818415-56-3
- Sequence
- VIKLSGRELVRAQIAISGMSTWSKRSL
- Purity (HPLC)
- ≥ 99.0%
- Common vial sizes
- 2 mg, 10 mg
- MOQ
- On request
- Lead time
- 14–21 days
- Storage
- -20°C, protect from light
Documentation available on request
- Lot-specific Certificate of Analysis (CoA)
- RP-HPLC chromatogram with peak integration
- ESI-MS identity confirmation (±0.5 Da)
- Sequence verification by LC-MS/MS
- Water content by Karl Fischer
- SDS / MSDS
- Counter-ion analysis (acetate vs TFA)
- Solubility / reconstitution guidance
- Stability data at −20 °C on request
Regulatory note
Sold for Research Use Only under the receiving laboratory's institutional and jurisdictional regulations. Not a finished dosage form, not labelled for human administration, not for in-vitro diagnostic use. For in vivo workflows, request bacterial-endotoxin and microbial-limit testing on the specific lot at quote stage.
Frequently asked questions
What does 'biased agonist' mean in the context of B7-33 and RXFP1 signaling?▾
Receptor signaling biology in the last decade has recognized that G-protein-coupled receptors (GPCRs) can engage multiple downstream signaling cascades, primarily G-protein-pathway and β-arrestin-pathway routes, and that different ligands can preferentially activate one cascade over the other. A 'biased' agonist is one that activates one downstream pathway more strongly than others. B7-33 is described as a biased RXFP1 agonist because it preferentially activates the ERK1/2 phosphorylation cascade (the pathway hypothesized to drive the anti-fibrotic and tissue-remodeling effects of relaxin) while showing reduced activation of the cAMP pathway (which contributes to relaxin's cardiovascular effects). The biased-agonist design strategy is intended to dissociate the desired therapeutic effects from the dose-limiting side effects.
How is B7-33 easier to synthesize than native two-chain relaxin?▾
Native human relaxin-2 (H2-relaxin) is a 53-amino-acid heterodimer with two chains connected by two interchain disulfide bonds plus one intrachain disulfide on the A-chain. Synthesizing the native molecule by SPPS requires synthesizing each chain separately, then performing controlled oxidative folding to form the three disulfide bonds in the correct regiochemistry, a process that produces 5-15% yield of the correctly-folded product against a background of scrambled disulfide isomers. B7-33 is a single 26-residue linear peptide with no disulfide bonds, synthesizable by routine SPPS at 50-80% yield. The simplification makes B7-33 substantially more accessible at research and commercial scale than native relaxin while preserving the RXFP1-agonism that drives the biological readouts of interest.