Circular dichroism (CD) spectroscopy
Circular dichroism measurements were made in a Jasco J-715 spectropolarimeter (Jasco Inc., Japan) using quartz cuvette, thermostated at 25 °C. Spectra were measured from 250 to 185 nm, with five scans at 100 nm/min, response time constant was 0.25 s, bandwidth was 1 nm, and slit width was 500 μm. Two hundred microliter aliquots of each protein were added to 1 cm pathlength cuvette. Spectra were background corrected, smoothed, and data were expressed in terms of [θ] using analysis function built into the Jasco software.