Optimal cleavage and oxidative folding of α-conotoxin TxIB as a therapeutic candidate peptide

Area of Science:

• Neuroscience
• Pharmacology
• Peptide Chemistry

Background:

• Alpha6beta2 nicotinic acetylcholine receptors (nAChRs) are key therapeutic targets for neuropsychiatric diseases like Parkinson's and addiction.
• Alpha-conotoxin (α-CTx) TxIB is a highly selective ligand for α6/α3β2β3 nAChRs, making it a promising therapeutic candidate.
• Efficient synthesis of α-CTx TxIB is crucial for extensive testing of its medicinal applications.

Purpose of the Study:

• To optimize the cleavage and oxidative folding processes for synthesizing α-conotoxin (α-CTx) TxIB.
• To identify key parameters influencing the yield and quality of synthesized α-CTx TxIB.

Main Methods:

• Systematic optimization of resin-bounded peptide cleavage conditions.
• Screening of 54 oxidative folding solutions to determine optimal conditions for α-CTx TxIB isomers.
• Evaluation of buffer type, redox agents, pH, salt concentration, co-solvent, and temperature.

Main Results:

• Co-solvent selection was identified as a critical factor for successful folding.
• Optimal folding conditions involved NH₄HCO₃ or Tris-HCl buffer at 4 °C with 40% DMSO co-solvent.
• Achieved complete oxidative folding of the globular isomer using GSH:GSSG (2:1) or GSH alone at pH 8–8.7.

Conclusions:

• Optimized cleavage and folding protocols significantly improve the yield of α-conotoxin (α-CTx) TxIB.
• The findings facilitate the large-scale production of this selective nAChR ligand for therapeutic development.
• This research paves the way for further investigation into the therapeutic potential of α-CTx TxIB in neurological disorders.