Maleimide Conjugates of Saxitoxin as Covalent Inhibitors of Voltage-Gated Sodium Channels
作者:William H. Parsons、J. Du Bois
DOI:10.1021/ja4019644
日期:2013.7.24
(+)-Saxitoxin, a naturally occurring guanidinium poison, functions as a potent, selective, and reversible inhibitor of voltage-gated sodium ion channels (Na(V)s). Modified forms of this toxin bearing cysteine-reactive maleimide groups are available through total synthesis and are found to irreversibly inhibit sodium ion conductance in recombinantly expressed wild-type sodium channels and in hippocampal nerve cells. Our findings support a mechanism for covalent protein modification in which toxin binding to the channel pore precedes maleimide alkylation of a nucleophilic amino acid. Second-generation maleimide-toxin conjugates, which include bioorthogonal reactive groups, are also found to block channel function irreversibly; such compounds have potential as reagents for selective labeling of Na(V)s for live cell imaging and/or proteomics experiments.
(+)-萨克霉素是一种天然存在的胍类毒素,用作电压门控钠离子通道(Na(V)s)的强效、选择性和可逆抑制剂。通过全合成得到的这种毒素的修饰形式带有半胱氨酸反应的马来酰亚胺基团,发现这些修饰形式不可逆地抑制了在重组表达的野生型钠离子通道和海马神经细胞中钠离子的传导。我们的发现支持了一种共价蛋白质修饰机制,其中毒素结合到通道孔道先于马来酰亚胺对亲核氨基酸的烷基化。还包括生物正交反应基团的第二代马来酰亚胺毒素缀合物也被发现不可逆地阻断了通道功能;此类化合物在选择性标记钠离子通道(用于活细胞成像和/或蛋白质组学实验)的试剂方面具有潜在用途。