Chemically synthesized dicarba H2 relaxin analogues retain strong RXFP1 receptor activity but show an unexpected loss of in vitro serum stability

Hossain, Mohammed Akhter, Haugaard-Kedstrom, Linda M., Rosengren, K. Johan, Bathgate, Ross A. D. and Wade, John D. (2015) Chemically synthesized dicarba H2 relaxin analogues retain strong RXFP1 receptor activity but show an unexpected loss of in vitro serum stability. Organic and Biomolecular Chemistry, 13 44: 10895-10903. doi:10.1039/c5ob01539a


Author Hossain, Mohammed Akhter
Haugaard-Kedstrom, Linda M.
Rosengren, K. Johan
Bathgate, Ross A. D.
Wade, John D.
Title Chemically synthesized dicarba H2 relaxin analogues retain strong RXFP1 receptor activity but show an unexpected loss of in vitro serum stability
Journal name Organic and Biomolecular Chemistry   Check publisher's open access policy
ISSN 1477-0520
1477-0539
Publication date 2015-09-09
Sub-type Article (original research)
DOI 10.1039/c5ob01539a
Open Access Status Not Open Access
Volume 13
Issue 44
Start page 10895
End page 10903
Total pages 9
Place of publication Cambridge, United Kingdom
Publisher Royal Society of Chemistry
Collection year 2016
Language eng
Formatted abstract
Peptides and proteins are now acknowledged as viable alternatives to small molecules as potential therapeutic agents. A primary limitation to their more widespread acceptance is their generally short in vivo half-lives due to serum enzyme susceptibility and rapid renal clearance. Numerous chemical approaches to address this concern have been undertaken in recent years. The replacement of disulfide bonds with non-reducible elements has been demonstrated to be one effective means by eliminating the deleterious effect of serum reductases. In particular, substitution with dicarba bonds via ring closure metathesis has been increasingly applied to many bioactive cystine-rich peptides. We used this approach for the replacement of the A-chain intramolecular disulfide bond of human relaxin 2 (H2 relaxin), an insulin-like peptide that has important regulatory roles in cardiovascular and connective tissue homeostasis that has led to successful Phase IIIa clinical trials for the treatment of acute heart failure. Use of efficient solid phase synthesis of the two peptide chains was followed by on-resin ring closure metathesis and formation of the dicarba bond within the A-chain and then by off-resin combination with the B-chain via sequential directed inter-chain disulfide bond formation. After purification and comprehensive chemical characterization, the two isomeric synthetic H2 relaxin analogues were shown to retain near-equipotent RXFP1 receptor binding and activation propensity. Unexpectedly, the in vitro serum stability of the analogues was greatly reduced compared with the native peptide. Circular dichroism spectroscopy studies showed subtle differences in the secondary structures between dicarba analogues and H2 relaxin suggesting that, although the overall fold is retained, it may be destabilized which could account for rapid degradation of dicarba analogues in serum. Caution is therefore recommended when using ring closure metathesis as a general approach to enhance peptide stability.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2016 Collection
School of Biomedical Sciences Publications
 
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