Universidade de Brasília - Pós-graduação em Biologia Animal, Brasília-DF, Brazil.
Toxicon. 2010 Aug 1;56(1):55-63. doi: 10.1016/j.toxicon.2010.02.030. Epub 2010 Mar 21.
Neurotoxicity is a major symptom of envenomation caused by Brazilian coral snake Micrurus frontalis. Due to the small amount of material that can be collected, no neurotoxin has been fully sequenced from this venom. In this work we report six new three-finger like toxins isolated from the venom of the coral snake M. frontalis which we named Frontoxin (FTx) I-VI. Toxins were purified using multiple steps of RP-HPLC. Molecular masses were determined by MALDI-TOF and ESI ion-trap mass spectrometry. The complete amino acid sequence of FTx II, III, IV and V were determined by sequencing of overlapping proteolytic fragments by Edman degradation and by de novo sequencing. The amino acid sequences of FTx I, II, III and VI predict 4 conserved disulphide bonds and structural similarity to previously reported short-chain alpha-neurotoxins. FTx IV and V each contained 10 conserved cysteines and share high similarity with long-chain alpha-neurotoxins. At the frog neuromuscular junction FTx II, III and IV reduced miniature endplate potential amplitudes in a time-and concentration-dependent manner suggesting Frontoxins block nicotinic acetylcholine receptors.
神经毒性是巴西珊瑚蛇 Micrurus frontalis 中毒的主要症状。由于可采集的材料量很少，这种毒液中还没有完全测序出神经毒素。在这项工作中，我们从珊瑚蛇 M. frontalis 的毒液中分离出了六种新的三指毒素，并将其命名为 Frontoxin (FTx) I-VI。毒素通过多次反相高效液相色谱法进行纯化。通过 MALDI-TOF 和 ESI 离子阱质谱法确定了分子质量。通过 Edman 降解和从头测序法对 FTx II、III、IV 和 V 的重叠蛋白水解片段进行测序，确定了 FTx II、III、IV 和 V 的完整氨基酸序列。FTx I、II、III 和 VI 的氨基酸序列预测有 4 个保守的二硫键，与先前报道的短链 α-神经毒素具有结构相似性。FTx IV 和 V 各含有 10 个保守的半胱氨酸，与长链 α-神经毒素具有高度相似性。在青蛙的神经肌肉接头处，FTx II、III 和 IV 以时间和浓度依赖的方式减少微小终板电位幅度，表明 Frontoxins 阻断烟碱型乙酰胆碱受体。
