Conotoxins are a group of cysteine-rich, neurotoxic peptides isolated from the venom of marine cone snails. MfVIA is a member of the μO-conotoxin family, and acts as an inhibitor of subtype 1.8 voltage-gated sodium ion channels (Na_V1.8). The unique selectivity of MfVIA as an inhibitor of Na_V1.8 makes it an ideal peptide for elucidation of the physiological functions of this voltage-gated ion channel. Previous experimental studies of point mutations of MfVIA showed that the double mutant [E5K,E8K] exhibited greater activity at Na_V1.8 relative to the wild-type toxin. The present study employs molecular dynamics (MD) simulations to examine the effects of various mutations at these key residues (E5 and E8) on the structure and dynamics of MfVIA. Five double mutants were studied, in which the positions 5 and 8 residues were mutated to amino acids with a range of different physicochemical properties, namely [E5A,E8A], [E5D,E8D], [E5F,E8F], [E5K,E8K], and [E5R,E8R]. Except for [E5D,E8D], all of the mutants tend to show decreased contacts at the N-terminus owing to the loss of the R1-E5 salt bridge relative to that of the wild-type, which subsequently lead to greater exposure and flexibility of the N-terminus for most of the mutant peptides studied, potentially rendering them more able to interact with other species, including Na_V1.8. Molecular docking studies of the peptides to Na_V1.8 via different binding mechanisms suggest that the [E5R, E8R] mutant may be especially worthy of further investigation owing to its predicted binding mode, which differs markedly from those of the other peptides in this study.

毒素是从海洋锥蜗牛的毒液中分离出来的一组富含半胱氨酸的神经毒性肽。MfVIA是μO-芋螺毒素家族的成员，并且是1.8型电压门控钠离子通道（Na _V 1.8）的抑制剂。MfVIA作为Na _V 1.8抑制剂的独特选择性使其成为阐明该电压门控离子通道生理功能的理想肽。先前对MfVIA进行点突变的实验研究表明，双突变[E5K，E8K]在Na _V处表现出更大的活性相对于野生型毒素1.8。本研究采用分子动力学（MD）模拟来检查这些关键残基（E5和E8）上的各种突变对MfVIA的结构和动力学的影响。研究了五个双突变体，其中第5位和第8位残基突变为具有一系列不同理化特性的氨基酸，即[E5A，E8A]，[E5D，E8D]，[E5F，E8F]，[E5K，E8K ]和[E5R，E8R]。除[E5D，E8D]外，由于R1-E5盐桥相对于野生型盐桥的丢失，所有突变体倾向于在N末端显示减少的接触，随后导致更大的暴露和柔韧性研究的大多数突变体肽的N末端的，可能使它们更能够与其他物种（包括Na _V）相互作用1.8。肽通过不同的结合机制与Na _V 1.8的分子对接研究表明，[E5R，E8R]突变体由于其预测的结合方式而特别值得进一步研究，这与本研究中其他肽的结合方式明显不同。