S6跨膜结构域的Y652氨基酸残基突变增强辣椒素阻断人类HERG钾通道的作用

发布时间：2018-04-01 21:22

本文选题：辣椒素　切入点：HERG　出处：《武汉科技大学》2009年硕士论文

【摘要】： 目的:研究辣椒素对野生型及突变型HERG离子通道的阻断作用,并试图探寻发生在S6结构域的突变位点是否是辣椒素与HERG结合的重要作用位点。方法:采用双电极电压钳技术测定表达在非洲爪蟾卵母细胞上的HERG离子通道电流(野生型,Y652A型,F656A型)。结果:辣椒素以浓度依赖性的方式阻断野生型HERG钾通道电流,其半最大效应浓度IC50为17.45μM。辣椒素的阻断作用不改变野生型HERG通道50%最大激活时的电位,但使稳态失活曲线向负值漂移。辣椒素可阻断关闭和开放两种状态的HERG通道。然而,同野生型HERG通道的阻断相比,Y652氨基酸残基突变为丙氨酸后其阻断作用明显增强,其IC50为5.68μM,而F656A突变与野生型的阻断效应之间没有明显的差别。同时我们还发现,使用25μM辣椒素后,Y652A型通道的稳态激活向正向漂移5mV,而失活参数向负值增大的方向漂移-29mV。结论:辣椒素结合并阻断关闭及开放状态的HERG通道,位于S6结构域的Y652是通道与辣椒素结合的重要位点。辣椒素对Y652A突变型HERG通道的阻断作用明显强于野生型,提示通道基因突变可能造成临床上有些患者对辣椒素特别敏感。
[Abstract]:Aim: to study the blocking effect of capsaicin on wild and mutant HERG ion channels and to explore whether the mutation site in S6 domain is an important binding site of capsaicin to HERG. Methods: double electrode voltage clamp technique was used to determine the current of HERG ion channel expressed on Xenopus oocytes. Results: capsaicin blocked the wild-type HERG potassium channel current in a concentration-dependent manner, and its half-maximum effect concentration IC50 was 17.45 渭 M. the blocking effect of capsaicin did not change the potential of the wild-type HERG channel at 50% maximum activation. But the steady-state inactivation curve was shifted to a negative value. Capsaicin could block both closed and open HERG channels. However, compared with the blocking of wild-type HERG channels, the blocking effect of Y652 amino acid residues mutated to alanine was significantly enhanced. The IC50 was 5.68 渭 m, but there was no significant difference between the F656A mutation and the blocking effect of wild type. We also found that the steady-state activation of Y652A channel with 25 渭 M capsaicin drifted forward by 5mV, and the inactivation parameter drifted negative by -29mV. Conclusion: capsaicin binds and blocks the closed and open HERG channels. Y652 located in the S6 domain is an important site for the binding of capsaicin to capsaicin. The blocking effect of capsaicin on Y652A mutant HERG channel is stronger than that of wild type. This suggests that mutations in the channel gene may cause some patients to be particularly sensitive to capsaicin.
【学位授予单位】：武汉科技大学
【学位级别】：硕士
【学位授予年份】：2009
【分类号】：R33

【参考文献】