Nanosecond-time-resolved infrared spectroscopic study of fast relaxation kinetics of protein folding by means of laser-induced temperature-jump

Elucidating the initial kinetics of folding pathways is critical to the understanding of the protein folding mechanism. Transient infrared spectroscopy has proved a powerful tool to probe the folding kinetics. Herein we report the construction of a nanosecond laser-induced temperature-jump （T-jump） technique coupled to a nanosecond timeresolved transient mid-infrared （mid-IR） spectrometer system capable of investigating the protein folding kinetics with a temporal resolution of 50 ns after deconvolution of the instrumental response function. The mid-IR source is a liquid N2 cooled CO laser covering a spectral range of 5.0μm （2000 cm^-1）-6.5μm （1540 cm^-1）. The heating pulse was generated by a high pressure H2 Raman shifter at wavelength of 1.9μm. The maximum temperature-jump could reach as high as 26±1℃. The fast folding/unfolding dynamics of cytochrome C was investigated by the constructed system, providing an example.

Nanosecond-time-resolved infrared spectroscopic study of fast relaxation kinetics of protein folding by means of laser-induced temperature-jump

Elucidating the initial kinetics of folding pathways is critical to theunderstanding of the protein folding mechanism. Transient infraredspectroscopy has proved a powerful tool to probe the folding kinetics.Herein we report the construction of a nanosecond laser-inducedtemperature-jump ($T$-jump) technique coupled to a nanosecond time-resolvedtransient mid-infrared (mid-IR) spectrometer system capable of investigatingthe protein folding kinetics with a temporal resolution of 50 ns afterdeconvolution of the instrumental response function. The mid-IR source is aliquid N$_{2}$ cooled CO laser covering a spectral range of 5.0$mu$m(2000 cm$^{-1}) sim $ 6.5$mu$m (1540 cm$^{-1})$. The heating pulsewas generated by a high pressure H$_{2}$ Raman shifter at wavelength of1.9$mu$m. The maximum temperature-jump could reach as high as 26$pm$1$^{circ}$C. The fast folding/unfolding dynamics of cytochrome $C$ wasinvestigated by the constructed system, providing an example.