Microfluidic-Based Diffracted X-ray Tracking Method for Real-Time Observation of Ion Channel Twist Motion Under Sequential Chemical Stimuli

Ion-channel proteins have become an important target for drug discovery whereas the significant gating dynamics in response to chemical stimuli have not been elucidated. Here we present a new microfluidic-based approach for the measurement of single-molecule dynamics with X-ray to capture the gating motions of ion channel proteins. A microchannel with silicon nitride (SiN) windows allows the recording of conformational changes of the KcsA potassium channel in response to the sequential different chemical stimuli. The captured large twisting motions of the KcsA channel suggest a novel gating dynamic and provide a way to understand protein dynamics.