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. 2020 Mar 29;18(4):180.
doi: 10.3390/md18040180.

Effects of Cyclization on Activity and Stability of α-Conotoxin TxIB

Xincan Li  1 , Shuai Wang  1 , Xiaopeng Zhu  1 , Dongting Zhangsun  1   2 , Yong Wu  1   2 , Sulan Luo  1   2
Affiliations

Effects of Cyclization on Activity and Stability of α-Conotoxin TxIB

Xincan Li et al. Mar Drugs. .

Abstract

α-Conotoxin TxIB specifically blocked α6/α3β2β3 acetylcholine receptors (nAChRs), and it could be a potential probe for studying addiction and other diseases related to α6/α3β2β3 nAChRs. However, as a peptide, TxIB may suffer from low stability, short half-life, and poor bioavailability. In this study, cyclization of TxIB was used to improve its stability. Four cyclic mutants of TxIB (cTxIB) were synthesized, and the inhibition of these analogues on α6/α3β2β3 nAChRs as well as their stability in human serum were measured. All cyclized analogues had similar activity compared to wild-type TxIB, which indicated that backbone cyclization of TxIB had no significant effect on its activity. Cyclization of TxIB with a seven-residue linker improved its stability significantly in human serum. Besides this, the results showed that cyclization maintained the activity of α-conotoxin TxIB, which is conducive to its future application.

Keywords: activity; cyclization; stability; α-conotoxin TxIB; α6/α3β2β3 nAChRs.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Amino acid sequences of cTxIB-4, 5, 6, and 7. The red letters indicate the four different linkers that were used to cyclize TxIB. The black bracket and connected line show the connection of the N-terminal and C-terminal of TxIB. The labeled black lines denote the disulfide connectivity.
Figure 2
Figure 2
Schematic of the synthetic route for cyclic analogues of α-conotoxin TxIB.
Figure 3
Figure 3
RP-UPLC and mass spectrometry analysis of the final cTxIB-4, 5, 6, and 7. (a) RP-UPLC chromatogram of cTxIB-4 with a retention time of 2.78 min; (b) ESI-MS data of cTxIB-4 with a mass of 1979.28 Da; (c) RP-UPLC chromatogram of cTxIB-5 with a retention time of 2.70 min; (d) ESI-MS data of cTxIB-5 with a mass of 2036.22 Da; (e) RP-UPLC chromatogram of cTxIB-6 with a retention time of 2.69 min; (f) ESI-MS data of cTxIB-6 with a mass of 2107.11 Da; (g) RP-UPLC chromatogram of cTxIB-7 with a retention time of 2.67 min; (h) ESI-MS data of cTxIB-7 with a mass of 2164.32 Da.
Figure 4
Figure 4
The relative current amplitude of TxIB and cyclized analogues at a concentration of 100 nM on rat α6/α3β2β3 nAChRs. The ND-96 solution was used as the negative control. Data points are mean ± SEM (n = 3–4). Statistical analysis was according to one-way ANOVA; * p < 0.05, ** p < 0.01, and *** p < 0.001 versus TxIB.
Figure 5
Figure 5
The relative stability of native TxIB and cyclic analogues in human serum. Error bars represent the mean ± SEM (n = 3).
See this image and copyright information in PMC

References

    1. Changeux J.P., Corringer P.J., Maskos U. The nicotinic acetylcholine receptor: From molecular biology to cognition. Neuropharmacology. 2015;96:135–136. doi: 10.1016/j.neuropharm.2015.03.024. - DOI - PubMed
    1. Gotti C., Moretti M., Bohr I., Ziabreva I., Vailati S., Longhi R., Riganti L., Gaimarri A., McKeith I.G., Perry R.H., et al. Selective nicotinic acetylcholine receptor subunit deficits identified in Alzheimer’s disease, Parkinson’s disease and dementia with Lewy bodies by immunoprecipitation. Neurobiol. Dis. 2006;23:481–489. doi: 10.1016/j.nbd.2006.04.005. - DOI - PubMed
    1. Hurst R., Rollema H., Bertrand D. Nicotinic acetylcholine receptors: From basic science to therapeutics. Pharmacol. Ther. 2013;137:22–54. doi: 10.1016/j.pharmthera.2012.08.012. - DOI - PubMed
    1. Shen G.S., Layer R.T., Mccabe R.T. Conopeptides: From deadly venoms to novel therapeutics. Drug Discov. Today. 2000;5:98–106. doi: 10.1016/S1359-6446(99)01454-3. - DOI - PubMed
    1. Singh S., Pillai S., Chellappan S. Nicotinic acetylcholine receptor signaling in tumor growth and metastasis. J. Oncol. 2011;2011:1–11. doi: 10.1155/2011/456743. - DOI - PMC - PubMed

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