title: Synthetic covalently linked dimeric form of H2 relaxin retains native RXFP1 activity and has improved in vitro serum stability.
abstract: Human (H2) relaxin is a two-chain peptide member of the insulin superfamily and possesses potent pleiotropic roles including regulation of connective tissue remodeling and systemic and renal vasodilation. These effects are mediated through interaction with its cognate G-protein-coupled receptor, RXFP1. H2 relaxin recently passed Phase III clinical trials for the treatment of congestive heart failure. However, its in vivo half-life is short due to its susceptibility to proteolytic degradation and renal clearance. To increase its residence time, a covalent dimer of H2 relaxin was designed and assembled through solid phase synthesis of the two chains, including a judiciously monoalkyne sited B-chain, followed by their combination through regioselective disulfide bond formation. Use of a bisazido PEG7 linker and "click" chemistry afforded a dimeric H2 relaxin with its active site structurally unhindered. The resulting peptide possessed a similar secondary structure to the native monomeric H2 relaxin and bound to and activated RXFP1 equally well. It had fewer propensities to activate RXFP2, the receptor for the related insulin-like peptide 3. In human serum, the dimer had a modestly increased half-life compared to the monomeric H2 relaxin suggesting that additional oligomerization may be a viable strategy for producing longer acting variants of H2 relaxin.
authors: Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC 3010, Australia ; School of Chemistry, University of Melbourne, Parkville, VIC 3010, Australia.
authors: Vinojini B
authors: VB
authors: Nair
authors: Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC 3010, Australia ; Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, VIC 3010, Australia.
authors: Ross A D
authors: RA
authors: Bathgate
authors: School of Chemistry, University of Melbourne, Parkville, VIC 3010, Australia.
authors: Frances
authors: F
authors: Separovic
authors: Department of Pharmacology, Monash University, Clayton, VIC 3800, Australia.
authors: Chrishan S
authors: CS
authors: Samuel
authors: Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC 3010, Australia ; School of Chemistry, University of Melbourne, Parkville, VIC 3010, Australia.
authors: Mohammed Akhter
authors: MA
authors: Hossain
authors: Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC 3010, Australia ; School of Chemistry, University of Melbourne, Parkville, VIC 3010, Australia.
authors: John D
authors: JD
authors: Wade
mesh_terms: D006333:Heart Failure; D006801:Humans; D055503:Protein Multimerization; D055550:Protein Stability; D020836:Protein Structure, Quaternary; D043562:Receptors, G-Protein-Coupled / Q000737:chemistry*; D018000:Receptors, Peptide / Q000737:chemistry*; D012065:Relaxin / Q000737:chemistry*
chemical_list: C095068:RLN2 protein, human; C417543:RXFP1 protein, human; D043562:Receptors, G-Protein-Coupled; D018000:Receptors, Peptide; D012065:Relaxin