CD measurements were performed on a Jasco 810 spectropolarimeter (Jasco, Easton, MD, USA) at 24 °C. The ellipticity of freshly re-folded samples (0.2 mg/ml protein in 10 mM ammonium bicarbonate, pH 7.4) was measured in the far-UV range between 185 nm and 260 nm in a 0.1 cm path length cylindrical cuvette (Hellma Cells, Plainview, NY, USA). The proteins were treated with 2X molar excess of tris(2-carboxyethyl)phosphine hydrochloride (TCEP) (Sigma-Aldrich, St. Louis, MO, USA), pH 7.4, at 24 °C for 16 h to reduce disulfide bonds. Far-UV profiles were the average of four independent scans, recorded wat a scan speed of 20 nm/min, with response time of 2 s and bandwidth of 1 nm. The molar ellipticity ([θ]) and the percent α-helix content were calculated as described previously [58 (link)].