Department of Food Science and Technology, Tokyo University of Marine Science and Technology, Konan-4, Minato-ku, Tokyo 108-8477, Japan.
Toxicon. 2011 Oct;58(5):430-8. doi: 10.1016/j.toxicon.2011.08.001. Epub 2011 Aug 7.
The oriental catfish Plotosus lineatus is known to contain proteinaceous toxins in the skin secretion as well as in the venom gland. However, detailed properties and primary structures of the skin toxins have not been clarified. In this study, two proteinaceous toxins (toxins I and II) were purified from the skin secretion of oriental catfish by a combination of gel filtration, anion-exchange HPLC and hydroxyapatite HPLC. Toxins I and II are monomeric simple proteins with almost the same molecular mass (35 kDa for toxin I and 37 kDa for toxin II) and are distinguishable from each other in isoelectric point (6.5 for toxin I and 5.1 for toxin II). Both toxins display lethal, edema-forming and nociceptive activities, although toxin I is significantly more potent than toxin II. The primary structures of toxins I and II were elucidated by cloning experiments based on the determined partial amino acid sequences. Toxins I (317 amino acid residues) and II (315 amino acid residues) share as high as 86% sequence identity with each other and are also highly homologous (56-75% identities) with the known fish natterin-like proteins.
鲶形目鱼类的胡子鲶 Plotosus lineatus 的皮肤分泌物和毒腺中都含有蛋白毒素。然而，皮肤毒素的详细性质和一级结构尚未阐明。本研究采用凝胶过滤、阴离子交换 HPLC 和羟磷灰石 HPLC 相结合的方法，从胡子鲶的皮肤分泌物中纯化得到两种蛋白毒素（毒素 I 和毒素 II）。毒素 I 和 II 均为单体简单蛋白，分子量几乎相同（毒素 I 为 35 kDa，毒素 II 为 37 kDa），等电点（毒素 I 为 6.5，毒素 II 为 5.1）也不同。两种毒素均具有致死性、水肿形成和痛觉活性，但毒素 I 的活性明显强于毒素 II。通过基于部分氨基酸序列测定的克隆实验阐明了毒素 I 和 II 的一级结构。毒素 I（317 个氨基酸残基）和 II（315 个氨基酸残基）彼此之间的序列同一性高达 86%，与已知的鱼类 natterin 样蛋白也具有高度同源性（56-75%的同一性）。
