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Updated: Aug 6, 2026

Synthesis and Structure Determination of µ-Conotoxin PIIIA Isomers with Different Disulfide Connectivities
Published on: October 2, 2018
Disulfide bond reduction corresponds to dimerization and hydrophobi-city changes of Clostridium botulinum type A
Jiunn-jye Wey1, Shiao-shek Tang, Tzong-yuan Wu
1Institute of Preventive Medicine, National Defense Center, Taipei, Taiwan 115, China.
Aim:
To determine the structure factors that mediate the intoxication process of botulinum neurotoxin type A (BoNT/A).
Methods:
Triton X-114 phase separation experiments and 1-anilino-8-naphthalene sulfonate binding assay were used to study the structural factor that corresponds to the hydrophobicity change of BoNT/A. In addition, sucrose density gradient centrifugation and a chemical crosslinking study were employed to determine the quaternary structure of BoNT/A.
Results:
Our results demonstrated that in other than acidic conditions, the disulfide reduction is the structural factor that corresponds to the hydrophobicity change of BoNT/A. The quaternary structure of BoNT/A exists as a dimmer in acidic solution (pH 4.5), although the monomeric structure of BoNT/A was reported based on X-ray crystallography.
Conclusion:
Disulfide bond reduction is critical for BoNT/A's channel formation and ability to cross endosome membranes. This result implies that compounds that block this disulfide bond reduction may serve as potential therapeutic agents for botulism.
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