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

TY - JOUR

T1 - Improving the stability of alpha-conotoxin AuIB through N-to-C cyclization

T2 - The effect of linker length on stability and activity at nicotinic acetylcholine receptors

AU - Armishaw, Christopher J

AU - Jensen, Anders A

AU - Balle, Lena D

AU - Scott, Krystle C M

AU - Sørensen, Lena

AU - Strømgaard, Kristian

PY - 2011/1/1

Y1 - 2011/1/1

N2 - Modification of α-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 α-conotoxin AuIB, a selective α3β 4 nicotinic acetylcholine receptor (nAChR) antagonist, to examine a range of oligopeptide linker lengths on the oxidative formation of disulfide bonds, activity at nAChRs, and stability to degradation by chymotrypsin. Upon nondirected 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 threefold decrease in activity for the α3β4 nAChR compared to wild-type-AuIB, although it was selective for α 3β4 over α7 and α 4β2 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 wild-type AuIB. As such, the cAuIB-2 globular isomer could constitute a useful probe for studying the role of the α3β 4 nAChR in a range of in vivo experimental paradigms.

AB - Modification of α-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 α-conotoxin AuIB, a selective α3β 4 nicotinic acetylcholine receptor (nAChR) antagonist, to examine a range of oligopeptide linker lengths on the oxidative formation of disulfide bonds, activity at nAChRs, and stability to degradation by chymotrypsin. Upon nondirected 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 threefold decrease in activity for the α3β4 nAChR compared to wild-type-AuIB, although it was selective for α 3β4 over α7 and α 4β2 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 wild-type AuIB. As such, the cAuIB-2 globular isomer could constitute a useful probe for studying the role of the α3β 4 nAChR in a range of in vivo experimental paradigms.

KW - Former Faculty of Pharmaceutical Sciences

U2 - 10.1089/ars.2010.3458

DO - 10.1089/ars.2010.3458

M3 - Journal article

C2 - 20649464

SN - 1523-0864

VL - 14

SP - 65

EP - 76

JO - Antioxidants and Redox Signaling

JF - Antioxidants and Redox Signaling

IS - 1

ER -