Aguilar Manuel B, López-Vera Estuardo, Imperial Julita S, Falcón Andrés, Olivera Baldomero M, de la Cotera Edgar P Heimer
Laboratory of Marine Neuropharmacology, Institute of Neurobiology, Universidad Nacional Autónoma de México, Juriquilla, Qro. 76230, México.
Peptides. 2005 Jan;26(1):23-7. doi: 10.1016/j.peptides.2004.10.012.
Peptide de7a was purified from the venom of Conus delessertii, a vermivorous cone snail collected in the Yucatan Channel, Mexico. Its amino acid sequence was determined by automatic Edman degradation after reduction and alkylation. The sequence shows six Cys residues arranged in the pattern that defines the O-superfamily of conotoxins, and several post-translationally modified residues. The determination of its molecular mass by means of laser desorption ionization time-of-flight mass spectrometry (average mass, 3170.0 Da) confirmed the chemical data and suggested amidation of the C-terminus. The primary structure (ACKOKNNLCAITgammaMAgammaCCSGFCLIYRCS*; O, hydroxyproline; gamma, gamma-carboxyglutamate; *, amidated C-terminus; calculated average mass, 3169.66 Da) of de7a contains a motif (gammaCCS) that has previously only been found in two other toxins, both from molluscivorous cone snails: TxVIIA from Conus textile and gamma-PnVIIA from Conus pennaceus. These toxins cause depolarization and increased firing of action potentials in molluscan neuronal systems, and toxin gamma-PnVIIA has been shown to act as an agonist of neuronal pacemaker cation currents. The similarities to toxins TxVIIA and gamma-PnVIIA suggest that peptide de7a might also affect voltage-gated nonspecific cation pacemaker channels.
肽de7a是从墨西哥尤卡坦海峡采集的食虫芋螺Conus delessertii的毒液中纯化得到的。其氨基酸序列在还原和烷基化后通过自动埃德曼降解法测定。该序列显示有六个半胱氨酸残基，其排列模式定义了芋螺毒素的O超家族，还有几个翻译后修饰的残基。通过激光解吸电离飞行时间质谱法测定其分子量（平均质量为3170.0道尔顿），证实了化学数据，并表明C端存在酰胺化。de7a的一级结构（ACKOKNNLCAITγMAγCCSGFCLIYRCS*；O，羟脯氨酸；γ，γ-羧基谷氨酸；*，酰胺化C端；计算平均质量为3169.66道尔顿）包含一个基序（γCCS），此前仅在另外两种毒素中发现过，这两种毒素均来自食软体动物的芋螺：Conus textile的TxVIIA和Conus pennaceus的γ-PnVIIA。这些毒素会导致软体动物神经系统中的去极化并增加动作电位的发放，并且毒素γ-PnVIIA已被证明可作为神经元起搏器阳离子电流的激动剂。与毒素TxVIIA和γ-PnVIIA的相似性表明肽de7a可能也会影响电压门控非特异性阳离子起搏器通道。
