Almost all marine snails within superfamily Conoidea produce venoms containing numerous neuroactive peptides. Most toxins characterized from members of this superfamily are produced by species belonging to family Conidae. These toxins (conotoxins) affect diverse membrane proteins, such as voltage- and ligand-gated ion channels, including nicotinic acetylcholine receptors (nAChRs). Family Turridae has been considerably less studied than their Conidae counterpart and, therefore, turrid toxins (turritoxins) have just been barely described. Consequently, in this work the most prominent chromatographic (RP-HPLC) fractions from the East Pacific species Polystira nobilis venom duct extract were isolated. The biological activity of six selected fractions was assayed on human (h) α7 AChRs expressed in Xenopus laevis oocytes. One of these fractions, F21, inhibited the acetylcholine-elicited response by 62 ± 12%. Therefore, this fraction was further purified and the F21-2 peptide was obtained. This peptide (at 5.6 μM) strongly and irreversibly inhibited the acetylcholine-induced response on hα7 and hα3β2 nAChRs, by 55 ± 4 and 91 ± 1%, respectively. Electrospray mass spectrometry indicates that the average molecular mass of this toxin is 12 358.80 Da. The affinity for hα3β2 nAChRs is high (IC₅₀ of 566.2 nM). A partial sequence without cysteines was obtained by automated Edman degradation: WFRSFKSYYGHHGSVYRPNEPNFRSFAS…; blastp search revealed that this sequence has low similarity to some non-Cys-containing turripeptides. This is the first report of a turritoxin from a species of the American Pacific and the second description of a turripeptide inhibiting nAChRs.

超家族Conoidea内的几乎所有海洋蜗牛都会产生含有大量神经活性肽的毒液。大多数以该超家族成员为特征的毒素是由属于科的科产生的。这些毒素（毒素）影响多种膜蛋白，例如电压和配体门控离子通道，包括烟碱乙酰胆碱受体（nAChRs）。Turridae家族的研究远不如Conidae家族，因此，几乎没有描述Turrid毒素（turritoxins）。因此，在这项工作中，从东太平洋物种Polystira nobilis毒液导管提取物中分离出最突出的色谱（RP-HPLC）馏分。对选定的六种组分的生物活性进行了测定，并在人（h）α7AChRs中表达。非洲爪蟾卵母细胞。这些馏分之一F21将乙酰胆碱引起的反应抑制了62±12％。因此，将该级分进一步纯化并获得F21-2肽。该肽（5.6μM）强烈和不可逆地抑制了乙酰胆碱诱导的对hα7和hα3β2nAChRs的应答，分别为55±4％和91±1％。电喷雾质谱表明该毒素的平均分子量为12 358.80 Da。对hα3β2nAChRs的亲和力很高（​​IC ₅₀566.2 nM）。通过自动Edman降解获得了不含半胱氨酸的部分序列：WFRSFKSYYGHHGSVYRPNEPNFRSFAS…; blastp搜索显示该序列与某些不含Cys的turripeptide具有低相似性。这是来自美洲太平洋物种的turritoxin的首次报道，也是turtureptide抑制nAChRs的第二个描述。