Engineered Protein Nanopore for Real-time Monitoring Single-molecule Reaction Between Cadmium Ion and Glutathione

摘要: Abstract The complexation of glutathione (GSH) with divalent cadmium ion has been used as a typical model for investigating the coordination chemistry sulfydryl-containing peptides and heavy metal ions, which is essential to understand mechanism intracellular detoxification. In this study, single-molecule reaction between GSH molecule Cd2+ was monitored in real time by nanoreactor that formed mutant (M113R)7 α-hemolysin (αHL) protein nanopore equipped novel per-6-quaternary ammonium-β-cyclodextrin (p-QABCD). pathways, intermediates, products could be recognized analyzing current fluctuations. highly dependent on solution pH value. Cd(GSH)2 only final product at 7.4, while both Cd2(GSH)2 were present 9.0. formation follows two possible pathways: (1) one first coordinates thiol group molecules form Cd(GSH)2, then second quickly incorporates deprotonated amino produce Cd2(GSH)2; (2) ions separately coordinate yield Cd2(GSH)1, binds Cd2(GSH)2. free-labeling free-modifying method monitoring chemical simple sensitive, would important further mechanisms detoxification metals. This work greatly expands research field technique.