The function of protein or nucleic acid strongly depends on its structure. Folding kinetic investigation helps to reveal the mechanism of how the molecule folds from the random coil into the final functional structure, which has highly been focused in chemical and biological science. Biomacromolecular folding usually occurs within a time scale of microseconds in their early stage. Conventional stopped-flow technique is widely used for investigating the kinetics of molecular reaction. However, the temporal resolution of approximately 1 ms of the stopped-flow method limits its applications to characterize the folding kinetics of microsecond or even sub-microsecond levels. In this presentation, we proposed several ultrafast mixing approaches with microfluidic chip for interrogating the early folding kinetics of nucleic acids and proteins. For example, we demonstrated a �crossed microfluidic beam� device as shown in , capable of completely mixing solutions within 0.6 �s, enabling for the first time the observation of cytochrome c folding beyond its folding speed limit (about 1.0 �s). This novel approach led to the discovery of a complex initial folding process hidden in the �burst� phase previously reported. Instead of a single exponential process, sequential events of non-exponential and exponential processes were discovered.

Ultrafast microfluidic mixers for investigating early folding kinetics of nucleic acids and proteins

248th National Meeting (2014)

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