Design, synthesis, and activity study of α-conotoxin A10LPnIA fluorescent probe / 药学学报

italic>α7 nicotinic acetylcholine receptor (nAChR) is widely distributed in the central and peripheral nervous systems, and is closely related to a variety of neurological diseases and inflammation response. α-Conotoxin [A10L]PnIA, as an antagonist targeting α7 nAChR, plays an important role in studying the physiological and pathological processes involved in α7 nAChR. [A10L]PnIA was labeled with fluorescein 5-carboxytetramethylrhodamine, and the active peptide ([A10L]PnIA-F) was obtained by a two-step oxidative folding procedure in vitro. The Xenopus oocyte expression system and the two-electrode voltage clamp technique were used to identify the potency of [A10L]PnIA-F fluorescent peptide, and its cytotoxicity was detected by mouse macrophages and CCK8 method. The molecular weight of [A10L]PnIA-F fluorescent peptide was identified by mass spectrometry as 2 077.28 Da, which was consistent with the theoretical value. Electrophysiological determination of its half-maximal inhibitory concentration (IC50) for α7 nAChR is 17.32 nmol·L-1, which is consistent with [A10L]PnIA (IC50, 13.84 nmol·L-1). The cytotoxicity test results showed that within the concentration range of 5 nmol·L-1 to 10 μmol·L-1, there was no significant inhibition on the growth of mouse macrophages. The results showed that the α-conotoxin fluorescent probe [A10L]PnIA could provide pharmacological tools for the research of α7 nAChR-related neurophysiological and pathological mechanisms.

Cyclization of α-conotoxin A10LPnIA with lysine assisted cyanuric chloride linker / 药学学报

The cyanuric chloride linkers have been used for cyclizing polypeptide, but not used for α-conotoxin, the peptides with rich disulfide bonds and more amino acid residues. In this study, cyclic peptides c[A10L]PnIA-1-4 were synthesized efficiently by lysine assisted cyanuric chloride linkers with 28.92%-52.00% yields. The activity evaluation showed that the IC50 values of c[A10L]PnIA-1 against α7 and α3β2 nAChR subtypes were 5 and 7 times higher than [A10L]PnIA respectively, and the subtype selectivity was maintained. The results of circular dichroism show that this cyclization method had no significant effect on its secondary structure. Compared with the commonly used head-to-tail cyclization in conotoxin cyclization, this method has the advantages of rapid reaction and high yield, which is expected to be further applied to the cyclization study of various α-conotoxins.