Improving the stability of alpha-conotoxin AuIB through N-to-C cyclization: The effect of linker length on stability and activity at nicotinic acetylcholine receptors

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Christopher J Armishaw, Anders A Jensen, Lena D Balle, Krystle C M Scott, Lena Sørensen, Kristian Strømgaard

Modification of alpha-conotoxin frameworks through cyclization via an oligopeptide linker has previously been shown as an effective strategy for improving in vivo stability. We have extended this strategy by investigating cyclic analogs of alpha-conotoxin AuIB, a selective alpha3beta4 nicotinic acetylcholine receptor antagonist, to examine a range of oligopeptide linker lengths on the oxidative formation of disulfide bonds, activity at nicotinic acetylcholine receptors, and stability to degradation by chymotrypsin. Upon non-directed random oxidation, the ribbon isomer formed preferentially with the globular isomer occurring as a minor by-product. Therefore, a regioselective disulfide bond forming strategy was used to prepare the cAuIB-2 globular isomer in high yield and purity. The cAuIB-2 globular isomer exhibited a three-fold decrease in activity for the alpha3beta4 nAChR compared to WT-AuIB, although it was selective for alpha3beta4 over alpha7 and alpha4beta2 subtypes. On the other hand, the cAuIB-2 ribbon isomer was shown to be inactive at all three nAChR subtypes. Nonetheless, all of the cyclic analogs were found to be significantly more stable to degradation by chymotrypsin than WT-AuIB. As such, the cAuIB-2 globular isomer could constitute a useful probe for studying the role of the alpha3beta4 nicotinic acetylcholine receptor in a range of in vivo experimental paradigms.
Original languageEnglish
JournalAntioxidants & Redox Signaling
Volume14
Issue number1
Pages (from-to)65-76
ISSN1523-0864
DOIs
Publication statusPublished - 2011

ID: 22360222