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Updated: Aug 18, 2026

Synthesis and Structure Determination of µ-Conotoxin PIIIA Isomers with Different Disulfide Connectivities
Published on: October 2, 2018
Theoretical and experimental NMR study of protopine hydrochloride isomers
Jaromír Tousek1, Katerina Malináková, Jirí Dostál
1Department of Theoretical and Physical Chemistry, Faculty of Science, Masaryk University, Kotlárská 2, CZ-611 37 Brno, Czech Republic. tousek@chemi.muni.cz
Abstract:
The 1H and 13C NMR chemical shifts of cis- and trans-protopinium salts were measured and calculated. The calculations of the chemical shifts consisted of conformational analysis, geometry optimization (RHF/6-31G** method) and shielding constants calculations (B3LYP/6-31G** method). Based on the results of the quantum chemical calculations, two sets of experimental chemical shifts were assigned to the particular isomers. According to the experimental results, the trans-isomer is more stable and its population is approximately 68%.
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